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Air Humidity Control Essential for Rose Production under Continuous Lighting.
Acta Hortic 711: 323-331
Rolf I. Pettersen, Leiv M. Mortensen, Roar Moe and Hans R. Gislerød.
Department of Plant and Environment Sciences,
Norwegian University of Life Sciences,
N-1432 Ås, Norway
[email protected]
Keywords: air humidity variation, roses, lighting period, powdery mildew, vase life, water loss
Abstract
The effects of diurnal variations in air humidity under continuous lighting period (LP) (24 h day-1 LP) on water loss from detached leaves were studied in two experiments. In experiment one two pot rose cultivars were grown daily periods of 0, 6, 12 and 24 h at 59% (low) combined with 81% (high) relative air humidity (RH) under continuous lighting. Plants grown at 18 h day-1 LP, 81 % RH were used for comparison. Parameters studied were growth, stomatal conductance and water loss under post-production conditions. In the second experiment two cut rose experiment plants were grown at daily periods of 0, 6, 12 and 24 h at 62% combined with 82% relative air humidity (RH) under continuous lighting. In addition, the effect of constant low (62% RH) and constant high (82% RH) was studied at 18 h day-1 lighting period. Parameters studied were vase life, development of powdery mildew and water loss of detached leaves.
In experiment one it was found that increasing lighting period from 18 to 24 h day-1 increased the number of flowers by 34 % and decreased the number of days until flowering by 12 % in pot roses. The rate of weight loss of detached leaves from plants grown at constant high RH and continuous lighting was significantly greater than from plant grown at constant low RH or diurnal variation between low and high RH. Measurements of stomatal conductance of plants grown at constant 81 % RH showed that the stomata suffered from lack of closure under post-production conditions and darkness. In experiment two a close relationship was found between the vase life and control of leaf water loss from detached leaves in the different treatments. Reducing the lighting period increased the vase life and decreased the water loss from the leaves both at constant low and constant high air humidity. In continuous light, six hours with low RH considerably increased the vase life as compared with constant high RH in both cultivars. The development of powdery mildew was significantly reduced when the lighting period was increased from 18 to 24 h day-1.
INTRODUCTION
The keeping quality of roses is reduced by continuous lighting (Mortensen and Fjeld, 1998; Mortensen and Gislerød, 1999) and high air humidity (Mortensen and Fjeld, 1998; Mortensen and Gislerød, 1999), and is related to malfunctioning stomata and excessive water loss in indoor conditions (Mortensen and Gislerød, 1999; Torre and Fjeld, 2001). Recently, it was found that a daily six-hour period with low air humidity was sufficient to enhance considerably the keeping life of cut roses as compared to constant high RH (Mortensen and Gislerød, 2004). However, these studies were carried out at a lighting period of 20 h day-1. It has so far not been investigated if a variation in the air humidity can counteract the negative effect of continuous lighting on keeping quality.
Continuous lighting of roses is desirable since dark periods are known to enhance the development of powdery mildew as shown with pot roses (Mortensen and Braut, 1998). This effect of a dark period on the development of mildew is probably related to a drop in air/plant temperature followed by a rise in air humidity. Variation in air humidity is known to cause mildew (Sphaerotheca pannosa var. rosae) in roses (Tammen, 1973; Wheeler, 1978), which in turn significantly reduces the decorative value of the stems. Until now, however, continuous lighting has not been recommended due to the adverse effect on the vase life of cut roses. Therefore, it is of great interest both from a practical point of view as well as from a plant physiological point of view to investigate the effect of air humidity variations under 24 h day-1 lighting period in cut roses. In order to do this, two experiments were conducted; the first concerning pot roses and the second concerning cut roses.
MATERIAL AND METHODS
Experiment one
Potted miniature rose plants (Rosa x hybrida ‘Isabel’ and ‘Pernile’) were grown in a mixture of peat:perlite (4:1 by volume) with four cuttings per 12 cm pot. During propagation; the minimum air temperature was 24C. The plants were cut back twice during production, on the second occasion to a height of 40 mm. Following the second cut, the plants were placed in separate greenhouse compartments. Ten days later, the plants were spaced to final density of 25 pots per m2. Supplementary lighting was provided by high pressure sodium (HPS) lamps positioned to deliver 250 25 mol m-2 s-1 PAR at plant height. The light was measured at plant height by means of Licor, Li-250 (Licor, Lincoln, Nebraska, USA) with quantum sensor. The CO2 concentration was kept at 800 l l-1 when the vents were closed by supplementation of pure CO2. The plants were watered regularly with a complete nutrient solution with an electrical conductivity of 2.5 mS cm-1 and the pH was kept between 5.5 and 6.0. Dry and wet sensors placed close to the plant canopy were used to monitor the temperature and relative air humidity (RH). A Priva greenhouse computer greenhouse computer was connected for recording, control and storage of climate data. The daily irradiance for the 18 and 24 h day-1 LP corresponded to a light sum of 16.2 and 21.6 mol m-2 day-1, respectively.
To investigate the effect of diurnal variation or constant air humidity on plants grown under 24 h day-1 LP, there were four treatments; constant low RH (59%), constant high RH (81%), or diurnally varying RH; 12h low RH/12h high RH or 6h low RH/18h high RH. In addition, plants were grown at 18 h day-1 LP and high RH used for comparison (Table 1). The water vapour pressure deficit of the air was 1000 and 500 Pa for the high and low RH conditions, respectively.
At the time of flowering, as defined by five open flowers per plant, ten plants per treatment of each cultivar were harvested and plant height, number of open flowers plus flower buds and total fresh and dry weights were recorded. Mean growth rate per day was calculated by dividing the dry weight by days until harvest.
At flowering, the upper five-leaflet leaves from five pots of each treatment were detached, in order to study the stomata response to dehydration. The weight of each leaf was measured on a digital scale immediately after detachment and the weight loss was recorded after 0.5, 1, 2, 3 and 4 hours under conditions simulating post-production climatic conditions. The temperature in the test room was 21C, the air humidity 40% RH (corresponding to 1500 Pa VPD) and a light intensity of 14 mol m-2 s-1 PAR was provided by fluorescent tubes (Philips TLD 33) for 12 h day-1. In addition, five pots from each treatment were given a 12 h dark period under indoor conditions prior to detaching the upper five-leaflet and measuring the weight loss. A total of 40 leaves per cultivar and treatment and were used for the water loss measurements.
Leaf conductance (mmol H2O m-2 s-1) was measured on the abaxial side of the upper five-leaflet with an AP4 porometer (Delta-T Devices, Cambridge, UK) on plants transferred to post-production conditions. Measurements under indoor conditions were made at the end of the 12 h light and 12 h dark period. Plants were regularly watered during the post-production measurements. The results are presented as an average of data collected during two days after transfer from greenhouse to post-production conditions. The porometer was allowed to stabilize at the room before the measurements were taken, placed in the room until the temperature had become stabilized. The cuticular transpiration on the upper side of the leaves was measured during the first day under indoor conditions.
The experiment was analysed using the SAS-GLM procedure (SAS Institute Inc., Cary, USA). Plants were used as replicates in the analysis.
Experiment two
Mature plants of the rose cultivars ‘Amadeus’ and ‘Orange Unique’ were cut back and replanted in a mixture of limed and fertilized peat (Humus-börsen), sand (5% by volume) and Perlite (33% by volume) in 3-litre pots. They were grown under supplementary light, and after the first flush the plants were pinched at a height of 25 cm, and five pots of ‘Amadeus’ and six pots of ‘Orange Unique’ were placed in each of six growth chambers with a growing area of 2.5 m2 each. The chambers were placed in a greenhouse compartment (previously described by Mortensen and Nilsen (1992)). The inlet air to the chambers came from a common air source, and the load with mildew spores was therefore the same in all chambers. The experiment included two lighting periods, 18 and 24 h day-1 (continuous). Under 18 h day-1 constant 62% or 82% RH were established, and under 24 h day-1 0, 6, 12 and 24 h with 62% RH combined with 82% RH was established in the different chambers.
The relative humidities of 62% and 82% corresponded to vapour pressure deficits (vpd) of 950 and 450 Pa, respectively. The humidity sensors (Vaisala HMP 35A) were calibrated using salt solutions of known concentrations (Vaisala HMK 11 Humidity Calibrator). Supplementary lighting was given by high-pressure sodium lamps (Philips SON/T) at a photosynthetic photon flux of 150±20 µmol m-2 s-1 (corresponding to a photon flux of 9.7 and 13.0 mol m-2 day-1 at 18 and 24 h day-1 lighting period respectively). The light was measured with a Lambda LI-185B (Licor, Lincoln, Nebraska, USA) instrument with quantum sensor above the plants. The contribution by daylight in the chambers (approximately 50% of the outside level) was on average 1.5 and 9.0 mol m-2 day-1 during first and second flush, respectively (Meteorological Station at Særheim Research Centre). The temperature in all chambers was maintained at 21.0±0.3°C and the CO2 concentration at 800±20 µmol mol-1.
The experiment started on 2 January and ended in the beginning of April. After the first flush (20 February) the treatments were switched between the chambers. Maximum five shoots were allowed to develop per plant. The plants were watered regularly with a complete nutrient solution as described previously (Mortensen and Fjeld, 1998), and soil salinity was kept between 2.0 and 3.0 mS cm-1, and pH about 5.5.
The rose shoots were harvested at flowering stage, and their length, fresh weight and the development of mildew were recorded. Altogether 23-28 roses were harvested per treatment and cultivar. The mildew infection was determined visually on a scale from 0 to 5: 0 = no visible mildew; 1 = 0-1%; 2 = 2-5%; 3 = 6-20%; 4 = 21-60% and 5 = 60-100% infected leaf area.
After harvest, 15 ‘Orange Unique’ or 18 ‘Amadeus’ cut roses were placed in vases (5 roses per vase) containing distilled water. The vases were placed in a room at 40±5% RH (corresponding to 1500± 200 Pa vpd) and 21.0±0.5°C to simulate indoor climatic conditions. Light at a level of 15 µmol m-2 s-1 photon flux was given for 12 h day-1 by means of fluorescent lamps (Philips TL 33). Vase life was determined as the time until the rose lost its decorative value, i.e. the development of bent necks or natural senescence of the flower.
At time of harvest, five leaves from the upper part of the shoots were picked off per plant in each chamber. The leaves were placed on a bench in the test room for keeping quality, and the water loss were determined by measuring the weight at start, after four hours and finally by determining the dry weight in an oven at 60°C.
The experiment was analysed using the SAS-GLM procedure (SAS Institute Inc. Gary, USA. Shoots were used as replicates in the analysis
RESULTS
Air humidity had generally little or no effect on the growth and flowering of roses, except for plant height, which showed a significant increase when grown at constant high RH. Constant low RH significantly decreased fresh and dry weight Table 1). Porometer measurements showed that the leaf conductance (mmol H2O m-2 s-1) of plants grown at a constant high RH under continuous lighting was higher during both light and dark when placed under indoor climatic conditions, then either plants under LH, 24h LP or HH, 18h LP. Plants grown under continuous light and HH had only 25% reduction in conductance at night. The leaf conductance of plants grown under continuous lighting with daily variations in RH did respond with stomatal closure in the dark and were similar to the plants grown with 18 h day-1 LP. No variation in the cuticular transpiration of the upper side of leaves was observed (Table 2). The water loss of detached leaves was affected by the RH regimes during production. Leaves grown at 24 h day-1 LP and constant high RH suffered a rapid water loss after detachment losing 50% of their fresh weight over the first two hours (Fig.1). By contrast, leaves from plants grown with part or all of each day at LH only lost 15% of their fresh weight after four hours. This was also observed after the plants were given a 12 h dark period before detaching and measuring the water loss of the leaves (Fig 2). The initial water loss could be slightly reduced by pre-treating the plants with a 12 h dark period before detaching the leaves (Fig 2)).
In experiment two the vase life strongly increased under continuous lighting in both flushes when a 6-h period of low RH was given as compared with constant high RH. The vase life was generally longer with 18 h day-1 lighting than under continuous lighting at constant high RH (data not presented). When the vase life and leaf water loss from roses grown at the different treatments were plotted against each other a significant negative correlation appeared (r2 = 0,673) (Fig. 3). Roses with a low water loss generally had a long vase life, and at increasing water loss a linear decrease in vase life took place. No roses with a high water loss have a long vase life, but the vase life of roses with a low water loss varied considerably. This means that if all roses with a vase life longer than 10 days were removed from the analysis, r2 increases significantly (data not presented).
The development of powdery mildew was always very low in continuous light in both cultivars. With a lighting period of 18 h day-1 (6 h dark period) the mildew infection was significantly increased as compared with in continuous lighting (Fig. 4.)
DISCUSSION
Air humidity had little or no effect on growth, which is in accordance with previous results obtained with roses (Mortensen and Fjeld, 1998; Mortensen et al. 2001).
Stomata that show little response to humidity or light are a well-known feature of in vitro grown plantlets developed under high humidity and low VPD, such plants have an impaired capacity to control water loss and are prone to desiccate. This effect has also been shown in greenhouse grown roses, developing under high humidity conditions ( Mortensen and Fjeld, 1998, Torre and Fjeld, 2001), resulting in excessive water loss and reduced keeping quality. Leaves developing at high RH fail to respond to darkness as a signal for closure of the stomata. In the present experiments, pot roses grown under continuous lighting and constant high RH did not respond to post-production conditions. Detached leaves rapidly lost water over the first few hours suggesting they were unable to close their stomata. However, plants grown under conditions inducing daily stomatal closure, caused by a period of darkness or low RH, were able to close their stomata indicates that continuous lighting does not disable stomata. Recently, it was shown that a 6-h drop period in air humidity was sufficient to enhance the keeping quality of roses grown with a dark period of 6 h (Mortensen and Gislerød, 2004), and this effect has now proved true also under continuous lighting. Slootveg and van Meeteren (1991) found that stomata of roses grown under a long photoperiod remained open in darkness, whereas those grown at a short photoperiod closed almost immediately. Lighting period has been found to interact with RH, leading to a decreased stomatal responsiveness, when increasing lighting period and RH (Mortensen and Fjeld, 1998; Mortensen and Gislerød, 1999). Continuous lighting alone, however, is probably not causing this malfunctioning, but will contribute to establish conditions resulting in little or no stomatal movement during leaf development. In this experiment, unresponsive stomata were observed at 82% RH. According to Ottosen et al. (2002) the threshold level for these detrimental effects of stomatal response tend to be approximately 85% RH for up to 12 h daily. However, in roses there seems to be great variation between cultivars in response to stomata malfunctioning (Mortensen and Gislerød, 1999). As shown in several reports the vase life of roses is closely linked to the ability of the leaves to control water loss at indoor conditions (Mortensen and Gislerød, 1999; Torre and Fjeld, 2001; Torre et al., 2001). Such a relationship has also been found in roses from a range of greenhouses, and measurements of water loss from detached leaves has proved to be a very good method to evaluate the potential keeping quality of cut roses (Mortensen, 2001). Also in the present study the vase life could generally be explained by the rate of water loss from detached rose leaves. However, below water loss rates of about 30% per four hours, vase life seems to be influenced by other factors than water loss rates. It should be noted that it is the climate conditions during leaf development that determines the water loss after harvest of the roses (Mortensen and Gislerød, 2000). This means that it is the period 10-20 days before harvest that is the most important period with respect to the influence of air humidity on vase life, since it is in this period that the most dominant leaves in the vase (upper five-leaflet leaves) of the rose shoot develop
The development of powdery mildew was reduced when the dark period was excluded by continuous lighting, in accordance with previous results with pot roses (Mortensen and Braut, 1998). However, at same time the vase life was significantly decreased as found with several rose cultivars (Mortensen and Gislerød, 1999). The present results show that it is possible to grow roses under continuous light without adversely affecting the vase life if the air humidity is dropped during a daily 6-h period. This finding probably will have a great positive influence on the rose production where powdery mildew is a problem and artificial lighting is used.
From the present study it might be concluded that a relative short-term variation in air humidity will significantly extend the vase life of roses under continuous lighting. The change in RH caused a change in vpd of the air by about 500 Pa vpd. In practise, during mild weather periods in spring and autumn it can be difficult to change the vpd that much by ventilation. An interesting question is therefore if a periodical air temperature increase which increase vpd will have similar effect as a drop in air humidity at constant temperature. In such a case, this might be an even better way to control keeping quality under continuous lighting.
ACKNOWLEDGEMENT
We thank Gavita AS and The Norwegian Research Council for economic support.
Literature Cited
Mortensen, L.M., 2001. Greenhouse climate and keeping quality of roses. Acta Hortic. 543, 199-205.
Mortensen,L.M.and Braut.E.,1998. Lighting strategy for pot roses (in Norwegian).Gartneryrket 88(7), 23-26.
Mortensen, L.M. and Fjeld, T., 1998. Effects of air humidity, lighting period and lamp type on growth and vase life of roses. Scientia Hort. 73, 229-237.
Mortensen, L.M. and Gislerød, H.R., 1999. Influence of air humidity and lighting period on growth, vase life and water relations of 14 rose cultivars. Scientia Hort. 82, 289-298.
Mortensen, L.M. and Gislerød, H.R., 2000. Effects of air humidity on growth, keeping quality, water relations and nutrient content of cut roses.Gartenbauwissenschaft 65, 40-44.
Mortensen, L.M. and Gislerød, H.R., 2004. Effect of air humidity variation on powdery mildew and keeping quality of cut roses. Scientia Hort.
Mortensen, L.M. and Nilsen, J., 1992. Effects of ozone and temperature on growth of several wild plant species. Norw. J. Agr. Sci. 6, 195-204.
Mortensen, L.M., Ottosen, C.O. and Gislerød, H.R, 2001. The effect of air humidity and K:Ca ratio on growth morphology, flowering and keeping quality of pot roses. Sci. Hortic. 90, 131-141.
Ottosen, C.-O., Mortensen, L. and Gislerød, H.R., 2002. Effect of relative air humidity on gas exchange, stomatal conductance and nutrient uptake in miniature roses. Gartenbauwissenschaft, 67(4), 143-147.
Slootweg, G. and van Meeteren, U., 1991. Transpiration and stomatal conductance of roses cv. Sonia grown with supplemental lighting. Acta Hort. 298:119-125.
Tammen, J.F., 1973. Rose powdery mildew studied for epidemics. Sci. Agric. 20, 10.
Torre, S. and Fjeld, T., 2001. Water loss and postharvest characteristics of cut roses grown at high or moderate relative air humidity. Scientia Hort. 89: 217-226.
Torre, S., Fjeld, T. and Gislerød, H.R., 2001. Effects of air humidity and K/Ca ratio in the nutrient supply on growth and postharvest characteristics of cut roses. Scientia Hort. 90, 291-304.
Wheeler, B.E.J., 1978. Powdery mildews in ornamentals. In: The Powdery Mildews (Ed. D.M. Spencer). Academic Press, London, pp. 411-441.
Tables
Table 1. The effect of constant high and low relative humidity (RH) and diurnal combinations of high and low RH under 24 h day-1 lighting period (LP) and constant high RH under 18 h day-1 LP on days until flowering, total number of flowers, plant height, fresh weight, dry weight and mean growth rate of both cultivars. Different letters following means indicate significant differences (α = 0.05)
RH LP
(h day-1) Days until flowering Total no. of flowers Plant height(cm) Fresh weight (g) Dry weight (g) Growth rate
(g day-1)
HH 18 39.7 a 15.9 a 33.8 a 137.3 a 35.7 a 0.90 a
HH 24 34.9 b 22.6 b 35.6 a 147.4 c 37.4 c 1.07 b
HH/LH
18/6 h 24 35.2 b 20.9 b 31.2 b 161.4 c 41.4 c 1.18 c
HH/LH
12/12 h 24 34.6 b 20.5 b 30.5 b 145.4 c 37.9 c 1.10 b
LH 24 35.6 b 21.3 b 29.3 b 127.5 b 34.5 a 0.97 a
Table 2. The effect of different RH regimes at 24 h lighting period during production on leaf conductance (mmol H2O m-2 s-1) in light and dark at post-production climatic conditions of two pot rose cultivars placed in a test room (Temperature 21ºC, 40 % RH and an irradiation level of 14 µmol m-2 s-1 for 12 h daily). Data presented are averages of both cultivars. S.E. is indicated as values (n = 4).
RH LP (h day-1) Conductance (lower side) (mmol H2O m-2 s-1) Conductance (upper side) (mmol H2O m-2 s-1)
Light Dark
HH 18 65.4 ± 10.1 20.3 ± 5.4 5.0 ± 2.2
HH 24 110.2 5.6 75.5 15.3 8.1 3.2
HH/LH
18/6 h 24 71.9 4.2 24.5 6.3 6.2 3.1
HH/LH
12/12 h 24 73.8 5.3 21.8 5.1 5.9 2.6
LH 24 69.5 4.6 23.4 3.6 6.5 2.4
Figures
Fig. 1. Leaf weight loss (relative values) of detached leaves under post-production climatic conditions as influenced by high (HH) and low (LH) relative air humidity (RH) and diurnal variations between high and low RH under 24 h day-1 compared to plants grown at high RH and 18 h day-1 LP. Bars indicate SE (n = 4).
Fig. 2. Leaf weight loss (relative values) of detached leaves after a 12 h dark period under post-production climatic conditions influenced by high (HH) and low (LH) relative humidity (RH) and diurnal variations between high and low RH under 24 h day-1 compared to plants grown at high RH and 18 h day-1 LP. Bars indicate SE (n = 4).
Fig. 3. Relationship between vase life and water loss from detached leaves
Fig. 4. Effect of the daily time period with low air humidity (62% RH) combined with 82% RH on the development of powdery mildew in cut roses grown at two lighting periods (LP).
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Roses are fairly thermophilic plants, so you need to maintain appropriate conditions for growing them in a polycarbonate greenhouse. The temperature at night should not drop below + 60 ° F. Daytime should be maintained between + 75-79 ° F. In addition, with this rose, it is necessary to provide additional lighting. The soil in the greenhouse should be warmed up to + 50-54 ° F.
Since the cultivation of roses in the greenhouse takes place directly in the ground, the height of its layer should be at least 3.3 feet. At the same time, do not overmoisten the root system with a high level of groundwater. To prevent this from happening, take care of drainage even at the stage of building the greenhouse. A polycarbonate greenhouse for winter growing of roses should be equipped with special air vents, the area of which should be at least 30% of the total glazing of the entire structure.
The beds with roses should be raised above the level of the tracks by at least 1′-1.3′. In this form, they will warm up better.
Greenhouse soil requirements for growing roses
To grow roses in a greenhouse, you need a well-fertilized, fertile soil with an acidity index equal to H 5.8-6.5. Before planting roses, you need to dig up the soil to a depth of 1.6′-1.9′, apply organic fertilizer. Roses need many nutrients to grow and bloom. However, these sissies in a closed environment are sensitive to excess salts in the soil. Therefore, fertilizing with mineral fertilizers should be strictly dosed and not more than 0.25% per liter of solution. Especially young rose seedlings suffer from salty soil. Therefore, before planting, experts recommend adding superphosphate. However, there should be plenty of potassium in the soil. Otherwise, roses grown with such difficulty will not stand for a long time in the cut.
Features of growing roses in greenhouses
The technology of growing roses in a greenhouse assumes that they are in one place for no more than 3-5 years. You must constantly enrich the soil with manure and superphosphate. In this case, apply fertilizers before the roses should begin their growth and flowering, i.e. after the end of the rest period. The dormant period can last two months, after the last cut of flowers in the fall. Plant new seedlings in the greenhouse no later than October. At the same time, the temperature in the greenhouse should be between 32-41 ° F. 12 days before the start of heating, the bushes are cut off, leaving the strongest shoots in the amount of 3-5 pieces.
At the same time, it is necessary to maintain air humidity equal to 70-80%, this is especially important for young plantings. In conclusion, I would like to say that winter growing of roses in greenhouses is a very difficult task. It is better to do this in areas with mild winters. In addition, you need to know which varieties of roses lend themselves well to growing in a polycarbonate greenhouse |
What Are the Ideal Growing Conditions for Roses?
Roses are perennial plants. A single rose bush can live for years. In fact, some varieties have a lifespan reaching several decades.
However, most growers consider springtime the traditional growing season for roses. As in most climates, roses bloom in the spring. This is true outdoors. But roses can bloom year-round in a greenhouse, or other controlled environment, where growers can replicate spring conditions.
It’s also important to note that roses prefer plenty of light. At least 6 hours of full sunlight is ideal, as long as it doesn’t get too hot. You can recreate this artificially as well, using lighting, such as LED grow lamps.
Rose care is also important when it comes to optimizing yields. To promote flowering, many rose growers lightly prune their rose bushes in the late winter and early spring. Pruning roses helps by removing dead organic matter and diseased canes. It triggers new growth and stimulates blooming.
What Is the Ideal Temperature for Rose Greenhouses?
As a perennial plant, roses are quite hardy and can survive in a wide range of temperatures. However, in order to promote growth and flowering, it’s best to maintain an optimal temperature range.
For most rose varieties, the ideal temperature range is around 65-75°F during the day (18-24°C), and 60-70°F overnight (15-21°C).
Lower temperatures may lead to your roses going dormant, as they would during the winter. Higher temperatures, reaching 85°F (29°C) and above, can lead to heat stress. This materializes in leaf scorch, wilting, and leaf loss.
Ideal Temperatures for Rose Cultivation:
Daytime – 65-75°F (18-24°C)
Nighttime – 60-70°F (15-21°C)
What Is the Ideal Humidity for Greenhouse Rose Cultivation?
As with most plants, humidity plays a major role in growth, flowering, and disease prevention. As a crop grown for its beauty, it’s important for the flowers to be vibrant, saturated, and blemish-free.
Humidity control is therefore highly important in rose greenhouses. The correct humidity range stimulates growth and optimal flowering and uniformity.
Fortunately, in a controlled environment, such as a greenhouse or glasshouse, you can create and maintain the ideal humidity. This allows growers to produce the highest quality roses possible.
The ideal relative humidity range for roses is around 70-80%. In terms of VPD, that’s 0.4-0.9 kPa during the day, and 0.35-0.75 kPa overnight.
These ranges are optimal for rose growth, development and blooming. However, it also helps in preventing diseases and molds that are common to rose production. Diseases such as powdery mildew can be devastating to rose bushes. Fortunately, you can completely prevent them by maintaining the correct humidity range.
Ideal Relative Humidity & VPD for Rose Cultivation:
Relative Humidity – 70-80% RH
Daytime VPD – 0.4-0.9 kPa
Nighttime VPD – 0.35-0.75 kPa
How to Create Ideal Humidity in a Rose Greenhouse
Rose greenhouses are naturally humid. Like all plants, they transpire constantly, evaporating water into the air. This inevitably leads to high humidity, reaching 100% relative humidity, in any closed space. Of course, high humidity slows growth, reduces flower quality, and leads to various diseases and molds.
Most traditional rose greenhouses reduce humidity by ventilating and heating. The ventilation removes the humid air, while the heating maintains an ideal temperature range.
However, heating and venting is highly inefficient. Removing humid air from the greenhouse also removes large amounts of heat. Growers then need to compensate for this heat loss, through more and more heating. Naturally, constant heating leads to high energy costs.
In addition to being inefficient, heating and venting may also be completely ineffective, in certain circumstances. Humid, rainy, or cold weather, as well as dark and cloudy days, often make ventilation redundant. If it’s not much drier outside than inside, ventilating won’t help reduce moisture in the greenhouse.
Using Dehumidifiers to Control Humidity
So, fully controlling humidity, at all times, at a high efficiency level, requires active dehumidification. Dehumidifiers like DryGair remove large amounts of moisture, specifically in a greenhouse space, by design. They do so actively, using patented circulation fans, combined with a condensation-based dehumidification system. This makes them incredibly efficient and effective at controlling humidity in commercial greenhouses and grow rooms.
Keeping your rose greenhouse closed and using dehumidifiers to control humidity, ensures ideal growing conditions, regardless of weather conditions. It also ensures a low energy input to achieve this task. Trials and grower experiences show energy savings of 50% on average, compared to traditional heating and venting.
Rose growers, Van der Hulst, in the Netherlands, save 35% on gas, for example. The company uses 24 DG-12 units in their advanced rose greenhouses.
Using Air Circulation to Improve Rose Production
Another important aspect of humidity control is air circulation. Proper airflow between the plants helps to disperse any pockets of humidity that may build up. This is a crucial factor in preventing mildew development, while also stimulating the plants and promoting optimal development.
All DryGair models include a patented air circulation module. DG units utilize powerful fans, with a unique 360° dispersal, that ensures uniform conditions throughout the greenhouse. Uniform growing conditions increases flower uniformity as well as quality, helping growing produce consistently beautiful roses. |
Temperature condition：
For growing healthy roses, it is necessary to maintain the air temperature at 22 °C during the daytime, and at night 20°C. In summer, the air temperature in the greenhouse can rise to 27 °C, while it is desirable to reduce the temperature to 16-17°C at night. If the air temperature in the greenhouse above 28 °C, leads to a loss of the quality of the rose.
In the daily temperature regime, two points are important: the transition from night to day and the transition from day to night. The intensity and duration of these transitions significantly affects the intensity of plant growth. A quick rise in temperature from night to daytime usually causes a weakening of the photosynthetic activity of the leaves. The shoots of flowers become thin and weak. The duration of the transition from night to daytime temperatures should be at least two hours. The air temperature has a strong influence on the size of the rose flower.
Humidity condition：
The relative humidity of the air is one of the main parameters when growing roses. For the active growth of roses, a relative humidity of 70-85% is necessary, in order to ensure optimal conditions for photosynthesis. With more than 90% humidity in the greenhouse, the risk of powdery mildew affecting roses increases significantly. This immediately leads to a sharp loss of the commercial quality of flowers. When the relative humidity in the greenhouse is less than 50%, the risk of damage to the rose by spider mites and powdery mildew also increases.
CO2 level：
Low CO2 level in greenhouse can limit highly productive photosynthesis. Carbon dioxide consumption is the growth of a plant. The intensity and productivity of photosynthesis increases by 50% when the concentration of carbon dioxide in the greenhouse air increases from 300 to 900 ppm.
Light condition：
The most important factor of plant growth is light, more precisely photosynthetic active radiation. The light energy of the plants in the greenhouse is mainly obtained from the sun, and can from artificial lighting. |
Where to plant
In a warm, sheltered, sunny location
In borders, in most soil types
In containers, especially dwarf cultivars
In a dedicated cut-flower border, so you can pick lots of blooms without spoiling the display in the garden
Chrysanthemums suit many garden styles, formal or informal, traditional or contemporary. Those with vibrant flowers work particularly well in exotic plantings, the pastel shades mingle sociably in cottage-garden borders, while the warm, burnished hues complement ornamental grasses.
When to plant
Plants that have been stored in a light frost-free place over winter can be planted outside in late spring, after the last frost (typically from mid May to early June).
Young plants raised from cuttings can be planted outside at the same time, once well rooted and growing strongly. Wait until after the last frost, having acclimatised them to outdoor conditions by hardening off few a few weeks beforehand.
Plants bought in summer can be put straight into borders and containers. If bought in late summer, they will be in full flower and provide instant colour.
How to plant
Chrysanthemums are easy to plant:
They like rich, fertile soil, so dig in la bucketful per sq m (sq yd) of well-rotted organic matter, such as garden compost, before planting
Space plants 30–45cm (12–18in) apart
Add a stake to support taller types
When planting in containers, use John Innes No 2 compost and a container with a diameter of at least 30cm (1ft)
Pinching out (stopping)
Once young plants reach about 20cm (8in) tall, in early summer, pinch out the main growing point to encourage branching. You can also pinch out the tips of sideshoots as they grow, until about mid-summer. This will help to create stockier plants that will carry more flowers.
Watering
Newly planted chrysanthemums, in borders or containers, need regular watering through the growing season. Never let the soil or compost dry out completely. But take care not to overwater too, as they dislike waterlogged conditions.
Feeding
To boost growth, apply a general fertiliser, such as Growmore or blood, fish and bone, towards the end of April.
You can also apply a nitrogen-rich feed in June, to further encourage lush growth. Use sulphate of ammonia or, for organic gardeners, dried poultry manure pellets, following the instructions on the pack.
During flowering, to maximise the display, you can give a weekly high-potassium feed, such as tomato fertiliser.
Mulching
Apply a thick layer of mulch to the soil surface after planting. This will help to hold moisture in the soil and prevent weed germination. Use well-rotted manure or garden compost.
If leaving plants in the ground over winter, insulate the roots with a thick layer of mulch in late autumn.
Removing some flower buds (disbudding)
Disbudding is a specialist technique used to produce very large blooms or well-balanced clusters to use as cut flowers or for exhibition:
On 'spray' chrysanthemums – these produce clusters (sprays) of flowers. If you remove the large central flower bud, you'll get a more uniform display of evenly sized blooms.
On single-flowered chrysanthemums – keep the main central flower bud and remove all the side buds and other shoots. The plant will then put all its energy into producing one spectacular flower.
Deadheading
Removing faded flowers regularly helps to keep the display looking its best. It also encourages new buds to form, extending the overall display.
See our guide to deadheading.
Overwintering
Most hardy chrysanthemums can survive temperatures down to at least -5˚C (23˚F). However, in much of the UK temperatures can fall below this, so it may be safer to lift and store plants over winter in light, frost-free conditions, such as a frost free greenhouse, a cool conservatory, porch or similar. Plants in exposed or poorly drained sites will particularly benefit.
Once flowering has finished, cut down the stems to about 20cm (8in) tall, to produce what is known as a stool
Lift the shortened plants and shake off the soil from the roots
Snip off any green shoots and leaves, so you have bare stems
Label each plant, if you have several different types
Stand the stools in a shallow tray, on a 5cm (2in) layer of slightly damp compost. Cover the roots lightly with loose compost.
Store in a cold but frost-free location, such as a cool greenhouse or conservatory, or a garage
Keep the compost just moist through the winter
In mild regions
Where temperatures are unlikely to fall below -5˚C (23˚F), especially in sheltered gardens with well-drained soil, you could risk leaving plants in the ground through winter.
Even so, it's best to give them some protection:
Cover the root zone with an insulating layer of mulch
Consider using a cloche to protect plants from winter rain
In containers
Plants in containers are particularly vulnerable to cold, so bring them indoors once flowering has finished. Keep them frost free, such as in a cool greenhouse or enclosed porch.
In very mild regions, you could risk leaving them outside, in which case:
Move them to a warm, sheltered spot, such as in the lee of a wall or under the eaves
Wrap containers in insulating layers of fleece, to protect the roots.
Make sure the compost doesn't get waterlogged – stand containers on bricks (or pot feet) to keep the drainage holes clear
The easiest way to make new plants is by taking cuttings in spring and to divide clumps. It's also possible to grow a few chysanthemum from seed.
By cuttings
In spring, use the vigorous new shoots as basal softwood cuttings. These root quickly and reliably to form plants that will flower in late summer:
Remove several shoots, 5–7.5cm (2–3in) long, from the outside of a clump. Cut with a sharp knife, right at the base, as close as possible to the crown
Remove the lower leaves and insert the cuttings into pots containing a mix of half peat-free multipurpose compost and half horticultural grit/perlite. Water in, then place in a propagator or cover with a clear plastic bag. Put in bright light (away from direct sunshine), at 10°C (50°F) or above
Ensure the compost is always moist, but not soggy, to encourage rooting
They should root in about three weeks. Move them into larger pots as they grow
They should be ready to plant out in a couple of months. Wait until after the last frost, harden them off carefully, and protect from slugs and snails
Plants that are in winter storage can be started into growth earlier than normal, so they produce shoots ahead of outdoor plants. Cuttings taken from these can have a head-start of several months:
In early January, bring plants out of winter storage into a greenhouse at 7–10°C (45–50°F)
Water them so the compost is thoroughly damp, then keep it just moist
Within three or four weeks, from mid-February, you should have large enough shoots to use as cuttings. Follow the method outlined above
By division
Older plants tend to lose vigour over time, so can be divided in spring, once growth has started. See our guide to dividing perennials.
By seed
A few cultivars are available as packeted seeds. Sow in spring at 15°C (59°F). They should germinate within two weeks, and the resulting plants should flower in the same year. |
Chrysant iernum (Dendrenthema grandiflora Tzvelev), Queen of the East, belongs to the
family Asteraceae, is one of the most important commercial flower used as cut as well
as loose flower and potted plant. It is native to the northern hemisphere chiefly Europe
and Asia It is preferred due to the wide range of shapes and sizes of flowers, brilliance
of colour tones, long lasting florets, and relative ease to grow all round the year round.
The Nett erlands is the foremost importer of chrysanthemum cut flowers and is the centre
for re-exiort to other countries.
III India, large flowered varieties are grown for cut flower and small flowered
varieties for making garland, wreaths and veni, religious offerings, for bedding and
potting purposes. Small flowered varieties are commercially grown in Tamil Nadu,
Karnatak a, Maharashtra. It is grown in an area of approximately 4000ha.
1here are about 160 species the genus Chrysanthemum among which the modem
autumn flowering perennial Chrysanthemum morifolium Ramat is most important. There
are abou: 2000 varieties have reported from world and about 1000 varieties from India.
1he commonly accepted classification of garden chrysanthemum is based on the
bloom shape, arrangement and di 'ectior; of growth. They are mainly classified as large
flowered (l3c.lasses) and small flowered (I Oclassess).
Uses:
• j,s a back ground in bordes by planting erect and tall varieties.
• Dwarf and compact variet.es are suitable for front row planting of borders and as
~ot culture.
• As a cut flower and loose ilower for making garland and hair adornment.
• Extra large bloom varieties used for exhibition.
Important varieties: Casa Granda, Snowdon White, Vesuvio, Melody Lane, Dancer,
Kikubiori, Super Giant, Christmas Carol, Gloria Red, Silvia Green, Dream Castle,
Taiching Queen, Helmy Pot, Sancho, Green Goddess, Golden. Splender and Bronze
Turner.
Therrnozero cultivars: Varieties flower at any temperature between 10° to 2ic but
most cc nstantly at 16°C night temperature.
40
Thermooositive cultivars: A minimum of 16°C required for initiation and ire: for
rapid init iation but delayed flowering.
Thermonegative cultivars: Bud initiation occurs at low or high temperature between
10° and ~,7oC but continuous high :emperature delay bud development.
Growing environment: Chrysanthemum being a short day plant can be grown as off
season rr ore profitably in the both climatically controlled and naturally ventilated
greenhouses. The partial modification of the growing schedule with photoperiodic
manipulation of light as light plays a very critical role in producing high quality cut
stems even in summer months.
Light: er rysanthemum requires long days for good vegetative growth and short days for
flowering responds to light for more than 13 hours photoperiod as critical long days and
remain vegetative. Therefore, its crop is programmed accurately by the application of
cyclic lig.itening and black out treatments manipulating day length between 13 and 7
hours as long and, short days, respectively. The former induces vegetative growth
(extensior. of stems) and later induces development of good stem length of cut flowers.
Most of the varieties need uninterrupted long days until reaching a vegetative height of
20-30cm before a short day treatment. On the other hand, decreased light intensity may
reduce photosynthesis and thereby quality of flowers may be reduced to produce thin and
low stem weight, faded flower colour and smaller sized buds.
Temperature: The night temperature determines the speed of bud formation. Low night
temperature results in more vegetative growth, taller plants, delay in flowering, longer
pedicels, sturdier plants and more intense flower colours. For nursery raising, the mother
plants shoild be grown at night temperature not lower than 18°C. However, for a normal
greenhous ~ crop and getting good flowering stems the optimum temperature should be
16-18°C d iring the night and 24-28oC during the day.
CO2: Enrichment of CO2 levels in air to 600-900ppm is recommended in closed
environment.
Re'lative:Iumidity: High relative humidity should be avoided. Low atmospheric
humidity I evels encourage high transpiration and respiration rates, resulting in hard and
dark growth. High atmospheric levels above 95% produce soft growth, which encourages
fungal and bacterial diseases. It is :lesirable to maintain a relative humidity of 60-7~%
during crop growth and flower bud development. |
To optimize chrysanthemum cultivation, especially in greenhouse environments:
Temperature Management:
Maintain an optimal temperature range between 17°C and 22°C for flowering.
During the LD (long-day) period, ensure temperatures between 12°C and 28°C to promote leaf unfolding.
Adjust day and night temperatures to influence internode length and stem elongation.
Consider applying short-term temperature drops for controlling plant height effectively.
Light Management:
Provide sufficient light levels, as higher irradiance tends to promote earlier flowering.
Manage day length to initiate flowering during the short-day (SD) period.
Cultivar Selection:
Choose cultivars that exhibit favorable responses to temperature variations, particularly in terms of flowering time and flower production.
Breed cultivars that perform well under lower temperature conditions to reduce energy consumption.
Biomass Production:
Monitor biomass production and partitioning to optimize growth.
Consider the influence of temperature on biomass accumulation, especially in relation to flowering and leaf-stem ratio.
Further Research:
Conduct additional studies to better understand the effects of temperature on chrysanthemum growth and development, particularly in the suboptimal temperature range.
Explore breeding strategies aimed at enhancing energy efficiency in chrysanthemum cultivation.
By implementing these strategies and staying informed about advancements in chrysanthemum cultivation, growers can improve efficiency and productivity while minimizing energy costs.
To optimize chrysanthemum growth, control the temperature during both the long-day (LD) and short-day (SD) periods. During the LD period, stem elongation is reduced at lower air temperature (AT), affecting final stem length. Manipulate the difference between day temperature (DT) and night temperature (NT) to control plant height, using methods like DROP treatment or adjusting DT and NT. Time to flowering depends on the number of days between the start of the SD period and flowering, with an optimum temperature usually between 17°C and 22°C. Monitor temperature during the SD period, as it affects flower bud initiation and development. Irradiance influences flowering time, with higher irradiance leading to earlier flowering. Manage temperature and irradiance to optimize flower production, aiming for an optimum temperature range between 15°C and 20°C. Nitrogen assimilation rate (NAR) per unit leaf area is lower at sub-optimal temperatures, but the contribution of stems to total photosynthetic capacity can be substantial, especially at lower temperatures. Optimize temperature conditions to maximize biomass production, considering both above-ground and below-ground biomass. |
Step-by-step Guide on Growing Chrysanthemums in A Greenhouse
How to Grow Chrysanthemums in A Greenhouse
1. Variety Selection
Selecting the right chrysanthemum varieties is crucial for successful greenhouse cultivation. It is essential to consider factors such as the type of bloom, its size, and color. Popular varieties include cushion, reflex, and decorative types, each offering a unique aesthetic appeal. Selecting disease-resistant varieties that are well-suited for greenhouse conditions ensures a healthier crop.
2. Greenhouse Site Preparation
Thoroughly prepare the site for the greenhouse, paying careful attention to every detail. It is crucial to select the most suitable soil, ensure it has good drainage, and maintain proper ventilation. By ensuring adequate ventilation, the greenhouse can effectively minimize the accumulation of humidity, thus reducing the likelihood of fungal diseases. Additionally, factors like the orientation and layout of the greenhouse should be considered as they contribute to creating an environment favorable for the growth of chrysanthemums.
3. Planting Chrysanthemum Cuttings
Chrysanthemums are commonly reproduced through the use of cuttings. Place the cuttings into the properly prepared soil, making sure to plant them at the correct depth. It is important to maintain adequate spacing between the plants to promote proper air circulation and minimize the risk of diseases.
4. Temperature Control
Temperature regulation plays a crucial role in the successful cultivation of chrysanthemums in a greenhouse, exerting its influence on every stage of the plant’s growth and flowering process. Chrysanthemums thrive within a specific temperature range of 15°C to 21°C during the day, with slightly cooler temperatures at night. It is imperative to maintain this optimal temperature range to facilitate the plant’s optimal development and abundant bloom production. To achieve this, greenhouse operators must invest in dependable climate control systems encompassing heaters for colder periods and ventilation for warmer periods, ensuring a consistent and suitable environment for the chrysanthemums. Any abrupt fluctuations in temperature can impose stress on the plants, resulting in undesirable consequences such as delayed flowering or bud abortion.
5. Lighting
Proper lighting is crucial when cultivating chrysanthemums in a greenhouse to achieve the best possible growth and blooming. Chrysanthemums are considered long-day plants, meaning they need a specific duration of light exposure to initiate and sustain the flowering process. In a greenhouse setting, it becomes crucial to incorporate additional lighting, particularly during shorter daylight periods, to fulfill these requirements. High-quality artificial lights with full-spectrum capabilities, such as high-pressure sodium (HPS) or light-emitting diodes (LEDs), can be strategically positioned to supplement natural sunlight effectively.
6. Watering
Chrysanthemums prefer consistently moist soil, however, it is crucial to strike a balance to prevent waterlogging, which can result in root rot. For greenhouse cultivators, it is recommended to establish a regular watering routine to maintain the soil’s moisture level without saturating it. The frequency of watering should be determined by various factors including the plant’s size, the temperature within the greenhouse, and the type of soil employed. It is advisable to water the plants in the morning, allowing the leaves to dry before nightfall to minimize the risk of fungal diseases.
7. Fertilization
Chrysanthemums have specific nutritional needs that vary throughout their growth stages. In the early stages, it is crucial to provide them with a well-balanced, water-soluble fertilizer that contains a higher proportion of nitrogen. This particular composition aids in the development of healthy foliage. However, as the plants transition into the budding and flowering stage, it becomes imperative to utilize a fertilizer that has a higher concentration of phosphorus and potassium. These nutrients are essential for promoting robust flower formation and enhancing the overall blooming process. It is advisable to regularly apply a complete and well-balanced fertilizer, with special attention given to micronutrients like iron to prevent any deficiencies. Furthermore, the incorporation of organic amendments and the use of slow-release fertilizers can contribute to a sustained availability of nutrients for the chrysanthemums.
8. Pruning and Pinching
Regular pinching is a common practice that is usually initiated when the chrysanthemums reach a height of approximately 6 inches. It involves the careful removal of the growing tips of young shoots to stimulate the growth of lateral branches. This technique ultimately leads to the development of a fuller and more compact plant with an increased number of flower buds. Moreover, pinching serves the purpose of synchronizing the flowering process and enhancing the overall visual appeal of the chrysanthemums. On the other hand, pruning involves a more selective approach, where specific stems or leaves are deliberately removed to effectively manage the size of the plant and redirect its energy towards desired areas, thereby promoting the growth of vigorous and vibrant blooms.
9. Support Structures
Chrysanthemum stems can become heavy with large blooms. By strategically positioning robust stakes or trellises within the greenhouse, crucial support is provided, preventing the stems from bending or breaking under the weight of the flowers. This becomes particularly crucial as chrysanthemums reach their peak of blooming, guaranteeing the overall well-being of the plants and optimizing the visual impact of the vibrant blossoms. Appropriately implemented support structures not only contribute to the structural soundness of the chrysanthemum plants but also facilitate improved air circulation, thereby reducing the risk of diseases within the greenhouse environment.
10. Pest and Disease Management
Chrysanthemums are susceptible to various pests, including aphids, mites, and thrips, as well as diseases like powdery mildew and botrytis. It is important to regularly examine the plants for any signs of infestation, such as distorted leaves or discoloration. To naturally control pests, it is recommended to implement preventive measures like introducing beneficial insects such as ladybugs and predatory mites. For mild infestations, neem oil and insecticidal soaps can be used. Furthermore, maintaining appropriate spacing between plants and ensuring proper ventilation can help reduce humidity, thus minimizing the risk of fungal diseases. In case symptoms appear or as a preventive measure, fungicides and bio-fungicides can be applied. Lastly, it is crucial to timely remove and dispose of any affected plant parts as this contributes to disease control.
11. Harvesting
Chrysanthemum blooms are ready for harvesting once they have reached their optimal stage of development. When the petals are fully opened and display vibrant colors. To ensure a successful harvest, it is recommended to use sharp and clean gardening tools like shears to cut the stems at a 45-degree angle. This type of cut promotes water uptake and helps maintain the overall health of the flowers. It is important to time the harvesting process when the blooms are in their early stages, as this will contribute to their longevity. Additionally, it is crucial to leave a portion of the stem intact during the harvesting process to prevent any damage to the plant and encourage future growth.
FAQs
What is the lifespan of a chrysanthemum flower?
The lifespan of a chrysanthemum flower is based on several factors, including the level of maturity during harvest, environmental conditions, and the care provided after harvesting. In general, if properly maintained, a freshly cut chrysanthemum flower can persist for a period ranging from one to three weeks. Regularly changing the water, pruning the stems, and ensuring a cool surrounding, the longevity of these flowers can be prolonged.
What temperature kills chrysanthemums?
Chrysanthemums exhibit sensitivity towards extreme temperatures, whereby both excessively high and low temperatures can pose potential risks to their overall well-being. When subjected to high temperatures, typically exceeding 32°C, chrysanthemum plants may experience heat stress and dehydration. This prolonged exposure to elevated temperatures can result in the foliage wilting, petals becoming scorched, and an overall reduction in the plant’s vitality. On the other hand, low temperatures can also prove detrimental, particularly if they drop below freezing point. Chrysanthemums are vulnerable to frost damage, which can lead to the rupture of cells and tissue damage, ultimately causing the foliage to turn black or become discolored.
Do chrysanthemums purify air?
Chrysanthemums do not play a significant role in enhancing the quality of indoor air. If you are looking for plants that purify the air consider other options such as spider plants, snake plants, or peace lilies. These plants have been extensively researched for their ability to effectively filter out common indoor pollutants. |
Package and Practices of Chrysanthemum
1. Common name- Chrysanthemum Botanical namenthemum morifolium. Family- Asteraceae Chromosome
number- 2n=36,45,47,51 Basic chromosome number- X= 9 They are mostly diploid,
tetraploid, hexaploid. •
ORIGIN- Asia and North- East Europe. Most species have its native place Asia
2. • Chrysanthemum is also called as the ‘Queen of the autumn’. • It is short day plant. •
It is a
partly woody erect perennial herb or sub shrub upto 1m in height with alternate thick
leaves. • The
inflorescence consists of many flower heads. Each flower head has numerous florets –
the disk florets
and ray florets. • It belongs to family Asteraceae. • The species of chrysanthemum have
fibrous root
system (shallow rooted plant), herbaceous perennial plant growing to 50-150 cm tall,
with deeply lobed
leaves and large flower heads, white, yellow or pink
3. . • Area under Chrysanthemum flower cultivation is 4000 ha land. • Productivity- For
loose
flower the productivity is 9- 10 tonnes/ha for main crop and 4-5 tonnes/ha for Ratooned
crop. • For cut
flower in spray type 1-1.2 lacs stems harvested in 1 ha area
.4. . • The chrysanthemum is one of the most important flower crops commercially grown
in different
parts of the world. • The Netherlands, Italy, Colombia, Spain, Germany and USA are the
important
countries where it is mainly grown under greenhouse conditions
5. • Commercial cultivation of Chrysanthemum is being done in Maharastra, Rajasthan,
MP, UP and
Bihar. • Its cultivation in Delhi, Kolkata, Lakhnow, Kanpur and Allahabad is mainly for
the sake of
decoration of surrounding and participating in flower source with the help of pot grown
plant.
6. . • There are many uses of Chrysanthemum flower and have great economic
importance are as: i.
Garden display. ii. Garland making. iii. Flower arrangement. iv. Small flowered varieties
are grown for
cut flower, making garland, wreaths, and religious offerings. v. Natural insecticide is also
obtained
called as Pyrethrin.
7. . • It is cold season crop which is grown throughout the world. • The most important
environmental factors influencing the growth and flowering of these plants are light and
temperature. •
The optimum temperature of 15.6° C is Chrysanthemum requires long days for good
vegetative growth and
short days for flowering. • The optimum temperature of 15.6° C required. • The relative
humidity of 70
to 90% is suitable for the plants. • Chrysanthemum is a short-day plant, meaning that
long nights (11
to 12 hours of darkness or longer, depending on cultivar) are required for rapid flower
initiation and
development.
8. . • Chrysanthemums will grow very satisfactorily in most well-prepared garden soils, if
it is
well-drained. A well- drained soil is a must, particularly if the plants are to be retained
over
winter. • They also respond best if the soil is slightly acid (pH 6.5) and if it contains
considerable
humus in the form of peat, leaf mold, or well-rotted manure. • The ideal soil for
chrysanthemum growing
is a well drained, sandy loam of good texture and aeration. • Good amount of organic
matter and pH of
6.5 is essential. It is a shallow fibrous rooted plant and is very sensible to water logged
conditions.
9. LARGE FLOWER 1. Incurved- The ray florets are incurved or overlapping. Florets
are not twisted
ane blooms are compact and globular when fully developed. Varieties- Snowball(white
flowers),
Sonarbangla, Chandrama, Graoe bowl. 2. Reflexed- It is just opposite to incurled. Ray
florets are
reflexed outside and overlap one another. Varieties- Creota, Dorothan, Citybeauty,
Sweetheart.
10. . 3. Spider- ray florets are large and tubular and usually curved. Varieties- Riresibangla,
Bidhan’s best, Mahatma Gandhi. SMALL FLOWERS 1. Korean single- The ray florets
are flat, strip like and
blooms are flat. Number of whorls of ray florets are 5 or less than 5 and disc is open.
Varieties- Cardinal, Chairman. 2. Korean Double- Similar to Korean Single but whorls of the ray
florets are more
than 5 and disc is open. Varieties- Jauntal wells, flirt, Manbhawan.
11. . 3. Decorating- Similar to Korean Double except that the flower is completely
double and
centre of the bloom is not visible. varieties- Arctic, Bluechip, Jublee, Alankar. 4.
Anemone- Ray
florets are small or may be twisted or curled but disc florets are well developed and
prominent.
Varieties- Calebcox. 5. Pompom- These are now getting popular and produce large
crop or small bloom.
Pinching once or twice is very helpful. Varieties- Camoo, Dandy, Eve, Nanakor.
12. . • Commercial varieties are- Kriti, Arka Swarna, Birbal Sahani, Baggi, Basanti,
Shanti, Arka
Ganga, Sadbhavna, Appu, Bindiya, Indira, Red Gold, Pankaj, Ajay, Sonali, Swarna,
Ravi kiran, Aakash,
Yellow Start, Rakhee. CO-1(Yellow) CO-2(Purple) Mdu-1(Yellow)
13. • Propagation is done by Seeds and Vegetative parts. Generally vegetative
propagation take
place. • Chrysanthemum is propagated vegetatively either through root suckers or
terminal cuttings.
Suckers : • Suckers arise from the underground stem and these are separated and
planted in prepared
nursery beds during January for stock plants. •
14. Chrysanthemum is propagated vegetatively either through root suckers or terminal
cuttings.
Terminal Cuttings : • Cuttings of 5-7 cm in length are taken form healthy stock plants in
June. The
cuttings are prepared by removing basal leaves and reducing the leaf area of remaining
leaves to half.
That Plant spacing 30 x 30 cm is maintained for the planting of Chrysanthemum
species. 15. .
The suckers are planted during June - July at 30 xis plant to plant and row to row
spacing is 30 cm.
30 cm spacing on one side of the ridges. Pinching is done once in 4 eeks after planting
to induce more
branching
.16. . Chrysanthemum is a heavy feeder and requires large amount of both Nitrogen and
Potassium. •
Nitrogen is required at early stage and the plants need P throughout the growth period.
As the buds
appear, the proportion of K should be increased and N should be reduced. • As the crop
responds well to
manuring, add 8-10 tonnes of well rotten FYM per acre. Apply 50 kg of Nitrogen, 160 kg
P2O5 and 80 kg
K2O as a basal dose. Spray GA3 at 50 ppm at 30, 45 and 60 days after planting to
increase the flower
yield • In Ludhiyana, the recommended dose of fertilizer is – Nitrogen- 400 kg
Phosphorus-400 kg
Potassium- 200 kg
17. . • Chrysanthemum requires frequent and thorough irrigation. • If rains are delayed
irrigation
is given twice a week in the first month and subsequently at weekly intervals. • The
frequency of
irrigation depends on the stage of growth, soil and weather conditions. • Proper
drainage system should
be maintained for chrysanthemum grown both in beds and in pots. • The height and
vigour of the
chrysanthemum plant can be influenced by regulating quantity and frequency of
irrigation. • In our
country, the method of irrigating the fields is byPinching : • Pinching is one of the most
important
operations in chrysanthemum culture. • Pinching refers to the removal of the growing
tips of the plant
to induce the growth of vegetative laterals. • It reduces the plant height, promotes
axillary
branching, delays flowering and helps in breaking rosetting. Disbudding : • This
operation is mostly
performed for large flowered and decorative type chrysanthemum. • Disbudding method
vary according to
the type of chrysanthemum grown. Many of the varieties are disbud or standard types,
in which the
largest terminal bud is retained and all axillary buds are removed. • Disbudding of spray
varieties is
very easy because in this case only the large apical bud is removed and the axillary
buds are allowed
to develop
18. . De-suckering: • Duringthevegetativegrowthphase,plantsgrow upwards.New
suckers
continuetodevelopfrombaseofplants. • For properandvigorousgrowthofplants,suckersare
removedfromtime
totime. Stakingofplants •
Stakingisnecessarytokeepplantserectandtomaintainpropershapeof plantsandbloom.
• Stakesare preparedmostlyfrombamboosticks.Stakingofplantsis
requiredforverticalsupportoftheplants.Onlyonestakeisusedwhena grower
needssinglebloomperplant
19. . • Weeds should be avoided in the greenhouse as well as fields. They deplete
moisture and
nourishment from plants. • Shortly after cuttings are established, carefully scratch the
ground to
uproot the weeds when they are small. • 2-3 hand weeding are required for proper
growth of the plant.
First weeding should be done one month after planting. • Herbicide can also be applied
to control weeds
from the field. Weeding and hoeing are yield generally done manually as and when
required, normally 8- 10 times yearly. • Crop suffers heavily if timely weeding is not given. Besides, control of
weeds the
soil is made loose porous to provide aeration.
20. . • The correct stage of harvesting depends upon the cultivar, marketing and
purposes etc. •
The flowers are harvested 3 months from the date of planting at an interval of 4 days. •
For floral
decoration and garlands, fully opened flowers are plucked with or without the peduncle.
Flowers are
packed loose in bamboo baskets or gunny bags and sent to retail markets for sale.
Harvesting of
Cutflowers: • Generally harvesting is done early in the morning. The stems are cut 20
cm from the
ground and are collected in trays or buckets containing cold water (15-18°C) and a floral
preservative
(Silver nitrate 25 ppm). • Alternately, the harvested stems are kept in 1000 ppm Silver
nitrate, for 10
seconds-10 minutes followed by placing in deionized water to prevent the blockage of
xylem by the
microorganisms
21. . • The yield of flowers varies according to types of cultivars, growing region, plant
density
and other management practices. • The average yield of loose flowers varies widely
from 8- 15 tonnes/
ha. • In southern states, the crop remains in the field for about ten months if it is
ratooned (six
months for plant crop an four months for ratoon crop). • Ratooning is seldom done now
days. Improved
varieties like CO.1 and CO.2 yields upto 1 t/ha in Tamil Nadu. • One can harvest the
flowers around 15
times. The yield ranges from 9 to 10 tonnes of loose flowers per acre.
22. • Chrysanthemums are graded based on the stem length, flower appearance,
number of flowers,
stem straightness, colour and freshness of flowers. • Standard Chrysanthemum are
graded into Blue, Red,
Green and Yellow, whereas spray types are graded into Gold, Silver and Bronze based
on the quality
parameters. • In Dutch market, spray chrysanthemums are graded into extra grade and
shorter grade. •
The • Loose flowers are packed in bamboo baskets or gunny bags for marketing. • The
capacity of bamboo
baskets ranges from 1 to 7 kg while gunny bags can accommodate 30 kg of loose
flowers.
23. • The storage is an important aspect of flower cultivation and marketing industries. It
is
stored under the protected condition so that it can be exported in distant countries.
Some prerequisite of storage of Chrysanthemum species are as follows- 1. It is kept under low
pressure and low
oxygen condition. 2. The place where flowers are stored must have low temperature
condition. 3. The
flowers must be placed vertically putting flower axis at the top. 4. In case of loose flower
value it
is stored or packed in bamboo basket or gunny bags.
24. . • Transporting of flowers is done through train, trucks, ships (refrigerated) etc. •
Before a
long day transport, it is better to keep flowers in water for at least 4 hours in a cold
store. • Among
the cut flowers chrysanthemum are amongst the top three best selling flower in all most
all major
flower consuming countries. • Few striking features which have made this flower
commercial in the
international market are: i. The standard type flowers fetch higher price though their
share is less.
ii. Spray types have smaller flower size and has major share in the world market. iii.
Maximum imports
from European nation are from June to October.
25. . • Pests:- Aphids (sucking type) - Thrips - Leaf miners - Mites • Diseases:- Sarcospora leaf
spot - Alternaria leaf spot - Fusarium wilt - Powdery mildew - Chrysanthemum stunt - Puccinia rust.
26. . • Several physiological disorder are seen in the species of Chrysanthemum flowers
due to
uneven climatic condition and seasons like- temperature change (high or low
temperature than required),
humidity i.e, moisture content in air ,and other plant function disorders , nutrient
deficiency and
toxicity , various symptoms are observed- a. Rotting of root b. Fading of colour of petals
of
Chrysanthemum flower c. Improper growth of plant and flower d. Chlorophyll deficiency
in the leave
region thus yellowing of plant
Package and Practices of Chrysanthemum
1. Common name- Chrysanthemum Botanical name- Chrysanthemum morifolium.
Family- Asteraceae
Chromosome number- 2n=36,45,47,51 Basic chromosome number- X= 9 They are
mostly diploid, tetraploid,
hexaploid. • ORIGIN- Asia and North- East Europe. Most species have its native place
Asia
2. • Chrysanthemum is also called as the ‘Queen of the autumn’. • It is short day plant. •
It is a
partly woody erect perennial herb or sub shrub upto 1m in height with alternate thick
leaves. • The
inflorescence consists of many flower heads. Each flower head has numerous florets –
the disk florets
and ray florets. • It belongs to family Asteraceae. • The species of chrysanthemum have
fibrous root
system (shallow rooted plant), herbaceous perennial plant growing to 50-150 cm tall,
with deeply lobed
leaves and large flower heads, white, yellow or pink
3. . • Area under Chrysanthemum flower cultivation is 4000 ha land. • Productivity- For
loose
flower the productivity is 9- 10 tonnes/ha for main crop and 4-5 tonnes/ha for Ratooned
crop. • For cut
flower in spray type 1-1.2 lacs stems harvested in 1 ha area
.4. . • The chrysanthemum is one of the most important flower crops commercially grown
in different
parts of the world. • The Netherlands, Italy, Colombia, Spain, Germany and USA are the
important
countries where it is mainly grown under greenhouse conditions
5. • Commercial cultivation of Chrysanthemum is being done in Maharastra, Rajasthan,
MP, UP and
Bihar. • Its cultivation in Delhi, Kolkata, Lakhnow, Kanpur and Allahabad is mainly for
the sake of
decoration of surrounding and participating in flower source with the help of pot grown
plant.
6. . • There are many uses of Chrysanthemum flower and have great economic
importance are as: i.
Garden display. ii. Garland making. iii. Flower arrangement. iv. Small flowered varieties
are grown for
cut flower, making garland, wreaths, and religious offerings. v. Natural insecticide is also
obtained
called as Pyrethrin.
7. . • It is cold season crop which is grown throughout the world. • The most important
environmental factors influencing the growth and flowering of these plants are light and
temperature. •
The optimum temperature of 15.6° C is Chrysanthemum requires long days for good
vegetative growth and
short days for flowering. • The optimum temperature of 15.6° C required. • The relative
humidity of 70
to 90% is suitable for the plants. • Chrysanthemum is a short-day plant, meaning that
long nights (11
to 12 hours of darkness or longer, depending on cultivar) are required for rapid flower
initiation and
development.
8. . • Chrysanthemums will grow very satisfactorily in most well-prepared garden soils, if
it is
well-drained. A well- drained soil is a must, particularly if the plants are to be retained
over
winter. • They also respond best if the soil is slightly acid (pH 6.5) and if it contains
considerable
humus in the form of peat, leaf mold, or well-rotted manure. • The ideal soil for
chrysanthemum growing
is a well drained, sandy loam of good texture and aeration. • Good amount of organic
matter and pH of
6.5 is essential. It is a shallow fibrous rooted plant and is very sensible to water logged
conditions.
9. LARGE FLOWER 1. Incurved- The ray florets are incurved or overlapping. Florets
are not twisted
ane blooms are compact and globular when fully developed. Varieties- Snowball(white
flowers),
Sonarbangla, Chandrama, Graoe bowl. 2. Reflexed- It is just opposite to incurled. Ray
florets are
reflexed outside and overlap one another. Varieties- Creota, Dorothan, Citybeauty,
Sweetheart.
10. . 3. Spider- ray florets are large and tubular and usually curved. Varieties- Riresibangla,
Bidhan’s best, Mahatma Gandhi. SMALL FLOWERS 1. Korean single- The ray florets
are flat, strip like and
blooms are flat. Number of whorls of ray florets are 5 or less than 5 and disc is open.
Varieties- Cardinal, Chairman. 2. Korean Double- Similar to Korean Single but whorls of the ray
florets are more
than 5 and disc is open. Varieties- Jauntal wells, flirt, Manbhawan.
11. . 3. Decorating- Similar to Korean Double except that the flower is completely
double and
centre of the bloom is not visible. varieties- Arctic, Bluechip, Jublee, Alankar. 4.
Anemone- Ray
florets are small or may be twisted or curled but disc florets are well developed and
prominent.
Varieties- Calebcox. 5. Pompom- These are now getting popular and produce large
crop or small bloom.
Pinching once or twice is very helpful. Varieties- Camoo, Dandy, Eve, Nanakor.
12. . • Commercial varieties are- Kriti, Arka Swarna, Birbal Sahani, Baggi, Basanti,
Shanti, Arka
Ganga, Sadbhavna, Appu, Bindiya, Indira, Red Gold, Pankaj, Ajay, Sonali, Swarna,
Ravi kiran, Aakash,
Yellow Start, Rakhee. CO-1(Yellow) CO-2(Purple) Mdu-1(Yellow)
13. • Propagation is done by Seeds and Vegetative parts. Generally vegetative
propagation take
place. • Chrysanthemum is propagated vegetatively either through root suckers or
terminal cuttings.
Suckers : • Suckers arise from the underground stem and these are separated and
planted in prepared
nursery beds during January for stock plants. •
14. Chrysanthemum is propagated vegetatively either through root suckers or terminal
cuttings.
Terminal Cuttings : • Cuttings of 5-7 cm in length are taken form healthy stock plants in
June. The
cuttings are prepared by removing basal leaves and reducing the leaf area of remaining
leaves to half.
That Plant spacing 30 x 30 cm is maintained for the planting of Chrysanthemum
species. 15. .
The suckers are planted during June - July at 30 xis plant to plant and row to row
spacing is 30 cm.
30 cm spacing on one side of the ridges. Pinching is done once in 4 eeks after planting
to induce more
branching
.
16. . Chrysanthemum is a heavy feeder and requires large amount of both Nitrogen and
Potassium. •
Nitrogen is required at early stage and the plants need P throughout the growth period.
As the buds
appear, the proportion of K should be increased and N should be reduced. • As the crop
responds well to
manuring, add 8-10 tonnes of well rotten FYM per acre. Apply 50 kg of Nitrogen, 160 kg
P2O5 and 80 kg
K2O as a basal dose. Spray GA3 at 50 ppm at 30, 45 and 60 days after planting to
increase the flower
yield • In Ludhiyana, the recommended dose of fertilizer is – Nitrogen- 400 kg
Phosphorus-400 kg
Potassium- 200 kg
17. . • Chrysanthemum requires frequent and thorough irrigation. • If rains are delayed
irrigation
is given twice a week in the first month and subsequently at weekly intervals. • The
frequency of
irrigation depends on the stage of growth, soil and weather conditions. • Proper
drainage system should
be maintained for chrysanthemum grown both in beds and in pots. • The height and
vigour of the
chrysanthemum plant can be influenced by regulating quantity and frequency of
irrigation. • In our
country, the method of irrigating the fields is byPinching : • Pinching is one of the most
important
operations in chrysanthemum culture. • Pinching refers to the removal of the growing
tips of the plant
to induce the growth of vegetative laterals. • It reduces the plant height, promotes
axillary
branching, delays flowering and helps in breaking rosetting. Disbudding : • This
operation is mostly
performed for large flowered and decorative type chrysanthemum. • Disbudding method
vary according to
the type of chrysanthemum grown. Many of the varieties are disbud or standard types,
in which the
largest terminal bud is retained and all axillary buds are removed. • Disbudding of spray
varieties is
very easy because in this case only the large apical bud is removed and the axillary
buds are allowed
to develop
18. . De-suckering: • Duringthevegetativegrowthphase,plantsgrow upwards.New
suckers
continuetodevelopfrombaseofplants. • For properandvigorousgrowthofplants,suckersare
removedfromtime
totime. Stakingofplants •
Stakingisnecessarytokeepplantserectandtomaintainpropershapeof plantsandbloom.
• Stakesare preparedmostlyfrombamboosticks.Stakingofplantsis
requiredforverticalsupportoftheplants.Onlyonestakeisusedwhena grower
needssinglebloomperplant
19. . • Weeds should be avoided in the greenhouse as well as fields. They deplete
moisture and
nourishment from plants. • Shortly after cuttings are established, carefully scratch the
ground to
uproot the weeds when they are small. • 2-3 hand weeding are required for proper
growth of the plant.
First weeding should be done one month after planting. • Herbicide can also be applied
to control weeds
from the field. Weeding and hoeing are yield generally done manually as and when
required, normally 8- 10 times yearly. • Crop suffers heavily if timely weeding is not given. Besides, control of
weeds the
soil is made loose porous to provide aeration.
20. . • The correct stage of harvesting depends upon the cultivar, marketing and
purposes etc. •
The flowers are harvested 3 months from the date of planting at an interval of 4 days. • For floral
decoration and garlands, fully opened flowers are plucked with or without the peduncle.
Flowers are
packed loose in bamboo baskets or gunny bags and sent to retail markets for sale.
Harvesting of
Cutflowers: • Generally harvesting is done early in the morning. The stems are cut 20
cm from the
ground and are collected in trays or buckets containing cold water (15-18°C) and a floral
preservative
(Silver nitrate 25 ppm). • Alternately, the harvested stems are kept in 1000 ppm Silver
nitrate, for 10
seconds-10 minutes followed by placing in deionized water to prevent the blockage of
xylem by the
microorganisms
21. . • The yield of flowers varies according to types of cultivars, growing region, plant
density
and other management practices. • The average yield of loose flowers varies widely
from 8- 15 tonnes/
ha. • In southern states, the crop remains in the field for about ten months if it is
ratooned (six
months for plant crop an four months for ratoon crop). • Ratooning is seldom done now
days. Improved
varieties like CO.1 and CO.2 yields upto 1 t/ha in Tamil Nadu. • One can harvest the
flowers around 15
times. The yield ranges from 9 to 10 tonnes of loose flowers per acre.
22. • Chrysanthemums are graded based on the stem length, flower appearance,
number of flowers,
stem straightness, colour and freshness of flowers. • Standard Chrysanthemum are
graded into Blue, Red,
Green and Yellow, whereas spray types are graded into Gold, Silver and Bronze based
on the quality
parameters. • In Dutch market, spray chrysanthemums are graded into extra grade and
shorter grade. •
The • Loose flowers are packed in bamboo baskets or gunny bags for marketing. • The
capacity of bamboo
baskets ranges from 1 to 7 kg while gunny bags can accommodate 30 kg of loose
flowers.
23. • The storage is an important aspect of flower cultivation and marketing industries. It
is
stored under the protected condition so that it can be exported in distant countries.
Some prerequisite of storage of Chrysanthemum species are as follows- 1. It is kept under low
pressure and low
oxygen condition. 2. The place where flowers are stored must have low temperature
condition. 3. The
flowers must be placed vertically putting flower axis at the top. 4. In case of loose flower
value it
is stored or packed in bamboo basket or gunny bags.
24. . • Transporting of flowers is done through train, trucks, ships (refrigerated) etc. •
Before a
long day transport, it is better to keep flowers in water for at least 4 hours in a cold
store. • Among
the cut flowers chrysanthemum are amongst the top three best selling flower in all most
all major
flower consuming countries. • Few striking features which have made this flower
commercial in the
international market are: i. The standard type flowers fetch higher price though their
share is less.
ii. Spray types have smaller flower size and has major share in the world market. iii.
Maximum imports
from European nation are from June to October.
25. . • Pests:- Aphids (sucking type) - Thrips - Leaf miners - Mites • Diseases:- Sarcospora leaf
spot - Alternaria leaf spot - Fusarium wilt - Powdery mildew - Chrysanthemum stunt - Puccinia rust.
26. . • Several physiological disorder are seen in the species of Chrysanthemum flowers
due to
uneven climatic condition and seasons like- temperature change (high or low
temperature than required),
humidity i.e, moisture content in air ,and other plant function disorders , nutrient
deficiency and
toxicity , various symptoms are observed- a. Rotting of root b. Fading of colour of petals
of
Chrysanthemum flower c. Improper growth of plant and flower d. Chlorophyll deficiency
in the leave
region thus yellowing of plant |
ow to grow chrysanthemums
The method for growing hardy chrysanthemums outdoors is similar to the process of growing dahlias. It is best to purchase rooted cuttings from a specialist supplier (such as Halls of Heddon), pot them up in spring, and keep them under cover (for example, in a cold frame), before planting out in sheltered, sunny borders in late spring or early summer. Chrysanthemums are thirsty, hungry plants, so enjoy well-drained soil that is retentive and fertile, and should be regularly fed and watered (when necessary) during the growing season. The plants can be mulched annually or biannually in spring or late autumn.
The method for growing tender chrysanthemums differs as the plants must be grown in a greenhouse or polytunnel or – in milder regions – grown outside and then brought under cover when the temperature drops later in the season. Although it may sound involved to cultivate chrysanthemums for the vase under glass, it is not complicated, and being able to harvest fresh flowers throughout November and December is a joy.
For a good crop of flowers, it is well worth pinching the plants out once they reach around 20 centimetres, in order to produce more shoots. Taller forms will require staking, especially when grown outside. For good flowering, liquid seaweed or tomato fertilizer provides the right dose of nutrients. After harvesting, these cutting chrysanthemums last a remarkably long time in the vase, which is one of the reasons growing them can become addictive. |
Key Greenhouse Conditions for Orchids
An orchid-friendly greenhouse is not difficult to create. You’ll need just five key things:
A high level of humidity.
Warm temperatures.
Fresh, clean air.
The correct amount of light for the variety.
A drop of 5-10 degrees (Celsius) during the night.
SLIGHT CONDITION CHANGES BY VARIETY
Orchids can be divided into a couple of general groups, based on the amount of light and temperatures they need to thrive.
Orchids that grow on the ground (usually called ‘terrestrial orchids’) don’t need as much light. They are used to forest floors and the covering of a leafy canopy overhead. They can also handle cooler temperatures.
Orchids that grow in the trees (called ‘epiphytic orchids’) require more light and slightly higher temperatures for best results.
Soilless Potting Medium & Temperature Control
Perhaps the biggest two changes in mindset for the aspiring orchid grower is that orchids do not grow in soil – they need what is called a ‘potting medium’ instead – and that they require not a constant temperature range, but rather a significant drop in night-time temperatures in order to bloom. If they don’t have both of these good things, or if they get too much of any one good thing, they will not do as well.
A third thing to keep in mind is that orchids in the wild grow up in trees, and so they get a lot of their nutrients from rain, not from the soil below them.
A great potting medium is a moisture of bark, peat moss, and perlite, often mixed in with some sphagnum moss or osmunda fibre. Usually, tree-growing orchids prefer more bark or osmunda fibre, whereas ground-growing species prefer more peat moss or sphagnum moss. The ratios of each depend on the species of orchid, so a little specific research or guidance is recommended for that – the seller should be able to tell you at the point of sale. Perlite helps the substrate drain well, so is used for both.
As far as temperature goes, you need a substantial drop at night, but it shouldn’t be more than ten degrees Celsius or less than five. That said, orchids suffer if they are in a cool draught, so avoid cooling with flowing air.
How Large Should Your Greenhouse Be?
Most of us want to spend as little as possible but get at least as much as we need. When it comes to buying your orchid-friendly greenhouse, start with what you need, and then do your pricing to see if it is within your reach. If budget is no object, however, then go big.
The greenhouse needs to be large enough for good air circulation without getting draughty, but it also needs to be kept within the right humidity levels and temperatures, which is more difficult the bigger the greenhouse gets. Orchids may not need a lot of room around them, but they also cannot touch, so if you are hoping for larger plants, you’ll need to leave plenty of space for their future growth.
Consider this example. Twenty Phalaenopsis orchids, at 50cm wide, would need at least 10m2 of greenhouse growing space. To this you’ll need to add considerations for the height of the plants, any storage you may want beneath them, any work room or walkways you’ll need, etc.
If you need a large greenhouse, we have a fantastic range for sale here, as well as a range of small and lean to greenhouses available at amazing prices.
Raise Plants Up
One great way to increase your control over temperature fluctuations is to raise up your plants on benches or shelves, to keep them from touching the ground or floor. A popular method is to use meal mesh benches or shelves with containers underneath to catch drain-off from watering. This allows the containers to conserve watering overflow and add it to the greenhouse’s humidity.
Weeds are also a problem for orchids – they really don’t like them – so adding a layer of small gravel, pebbles, or bark can discourage weed growth and keep your plants healthier.
Controlling the Greenhouse Growing Environment
A good greenhouse environment, especially for orchids, requires the keeper to maintain four major conditions: Humidity, circulation of air, light levels, and watering.
HUMIDITY
Orchids do best in humidity levels between 60 and 80%. Water trays are a good way to boost humidity, especially in the sunny times of year, but it does require occasional cleaning of the trays to prevent musty smells and other potential pest problems. Some prefer to mist the greenhouse with a fine spray at intervals. This system can cost a bit more but works very well and is often automatic.
A word of caution though, commercial misters do not have a fine enough spray and may lead to standing water and subsequent rot. Better to use something made to purpose.
Monitor your greenhouse humidity levels using a simple humidity gauge.
VENTILATION
Air flow is easiest in summer, when a set of open vents or roll-up windows can do the trick. Closing these at night is a good idea though, even if temperatures are not expected to fall dangerously low – an unexpected wind or storm can easily damage the plants.
If the days are too dry, hot, and still for your orchids, you’ll need to help out through artificial means. Small fans placed below the plant level will suffice, but make sure that they do not point directly at the plants or blow too hard.
Spacing orchids farther apart also aids in circulation but can lower humidity. Your greenhouse should not smell stale or musty – if it does, you need more airflow.
Browse ventilation options here.
LIGHTING
Orchids like indirect light – not direct light – so a cover or some light shade is needed. Sometimes this is achieved through placement of the greenhouse itself, below tree cover or near a larger building, but if it is out in the open, you may need some netting or other covers to create the same protection.
Most orchids thrive in twelve to fourteen hours of light on a summer’s day, and from ten to twelve hours on a winter’s day.
In the UK, a south-facing greenhouse should have enough light in the summer, but even then it will need some help in the winter to provide the light the orchids need. A few fluorescent bulbs or grow light at the top of the greenhouse (15-20cm above the plants) should suffice.
You can use timers to automatically turn the light on and off, or you can set your own timer to do it manually – which is a great time to check on the plants and other conditions anyway.
Well-lit orchids should have bright, vibrant green leaves. Yellowing or dark brown on the leaves can be a sign of insufficient lighting (or perhaps another problem).
bright pink orchid flower
WATERING
It is more difficult to water orchids (properly) than it is with other plants. Too much water and the roots will rot. Too little and the roots dry and the leaves fall. The goal is to keep them continually moist, but never sopping wet… just like the rainforest habitats where many of them developed.
Sound easy? Well, we’re not finished yet.
Some orchids like the growth medium to dry out between watering – completely dry out. Schedules can help reduce stress over this, but there is no substitute for a careful eye on things.
Your orchids won’t need as much water in the summer months if you live in a warmer climate, because the ambient air will be more humid than in colder areas. You’ll still need to water regularly though, and to check on the growing medium to make sure it is appropriate to the variety of orchid you are growing.
Mythbusting: No Ice Cubes
There is a practice out there that looks like a handy trick to keep your orchids watered, but is actually quite harmful to them; this is the ice cube method. The effect of having ice cubes on or near the growing medium is the same as putting your orchid in the middle of a cold draught. It will not like it and the damage caused to the roots might be enough to kill the plant off entirely.
An exception to this is if you have an orchid from ASDA or somewhere similar and you plan to throw it out once it is done blooming. For a long-living, healthy orchid though, avoid the ice cube method entirely.
Watering Varies by Growing Medium
The degree and method of watering will depend somewhat on the growing medium you are using. Sphagnum moss doesn’t retain water well and so it tends to dry out very easily and quickly. Once dry, it is difficult to get it to absorb water again. The key here is to water frequently (but in smaller amounts) to keep its limited water-retention ability running at its peak.
Bark chips dry out quickly too – at the top! – but will retain water for a much longer time at the bottom of the container. When checking for dryness in a bark-rich medium, always check at the bottom to make sure you are not overwatering based on a dry upper surface.
Peat moss is similar to bark, but as a rule of thumb, you only need to water it again when the top 5cm are dried out. This should maintain an optimal overall moisture level.
bright purple orchid flower
How to Avoid Common Issues
There are a few common problems that come along with growing orchids. A couple of them are the result of overwatering: mildew or fungus can develop on the growing medium. Thrips and root rot are two other problems common to orchids.
Don’t despair. These can be serious problems for your orchids, but they are not without their solutions.
THRIPS
Thrips are tiny insects that crawl around the flowers and buds, eating away at the tissue. Midges look a lot like thrips and the two are often confused for each other. The good news is that both can be taken care of using the same methods. The best way to deal with them is with a three-tiered approach:
Apply an insecticidal soap treatment to the tops and undersides of leaves, the stem and leaf connections, and (if possible) to the roots as well. Tip the plant upside down to drain away the excess from the leaf nodes.
Follow this up with sticky tapes to trap the insects as they flee the soap.
Predatory mites can also take a big bite out of a population of thrips, but this is only recommended for orchids in a greenhouse setting (you won’t want them infesting your house).
Some people prefer to drown out the thrips, but those who do this must be careful not to cause a fungal or rot problem with the excess water.
MOLD, MILDEW AND FUNGUS
Mildew and fungus can be taken care of using the same method.
Mix four teaspoons of baking soda in a gallon (4 litres) of water and add two teaspoons of insecticidal soap.
Dampen a washcloth in the mixture and wipe the leaves of the orchid, gently covering as much of them as you can.
Repeat twice a week until the mildew or fungus are gone. (You may want to continue for another week just to be thorough.)
If this method does not work, you may need to try a copper fungicide. If you do, carefully follow the directions on the package.
It is recommended to repot the orchid as well, once the problem has been taken care of, so you can use a fresh pot, fresh growing media, and you can also get at the roots for a quick and gentle wash. This should minimise the chances of the problem recurring. Dispose of the infected soil and disinfect the pot thoroughly (with a fungicide, baking soda mix, or a mixture of 30% bleach and 70% water) before reuse.
If these don’t work, you’ll have to get really tough. Throw out infected media and pots, and submerge the orchid in full strength hydrogen peroxide… if you keep it at all. Remember, these problems can jump from one plant to another too, so you’ll want to isolate infected plants and thoroughly clean the original area to protect the others.
ROOT ROT
Root rot is a serious form of fungus or mould, and cannot be treated in the same way as discussed above. Orchids hit by root rot can take a year or more to recover. Identify root rot by the black, squishy roots that fall away from the plant. The black discolouration might even reach the stem.
Repotting orchids every two years can discourage root rot, as can maintaining a steady and appropriate amount of moisture in the growing media.
If you do find root rot on your orchids, follow these steps to fight it:
Remove the plant from the pot and clean away all old growing media.
Clean away (remove) all affected roots and tissue from the plant. (If the stem is infected, the plant is unlikely to recover and will likely need to be disposed of).
Rinse the plant thoroughly with water.
Apply fungicide to the tissues around the infected areas.
Plant the orchid in sphagnum moss for a recovery period, paying close attention to moisture levels and ensuring it has plenty of fresh, circulating air.
If the plant hasn’t recovered in two months, it is very unlikely to survive at all.
How to Get Better Blooms
The primary attraction people have to orchids is their spectacular flowers. Since they don’t flower all of the time (but wouldn’t that be wonderful?!), most orchid fans take care to get the most out of the flowering periods, making sure they are full and last as long as possible. One key to achieving this is proper fertilising of the growth media – but there are other tricks too.
Light is key. An additional two hours per day can trigger a bloom.
Phosphorous can encourage a strong, early bloom too.
A balanced fertiliser (like 10-10-10 or 12-12-12) will ensure they have all they need when they do start to bloom. Use half of the recommended dose of fertiliser every month, as orchids don’t need (and don’t like) the full dose needed by many other plants.
Winter Care
As tempting as it may be to coax orchids into a winter bloom, we recommend you save the blooming for the summer months. During winter, care should be focussed on building up a healthy foundation prior to blooming.
In cooler areas, it is best to keep orchids inside throughout the winter months. Greenhouses are a great option too, if you are in an area of suitable temperatures. See the temperature guidelines above, and find out what temperature range best suits the variety you are growing. In general, night-time temperatures should be 5-10 degrees (Celsius) cooler than in the daytime.
The smaller the greenhouse, the easier it will be to heat and humidify, but it can be susceptible to a lack of air circulation – yet you want to avoid cold draughts! Insulating your greenhouse is a great way to keep heat contained, but it also cuts down on sunlight getting through, perhaps making lights a necessity. Insulation can also hamper circulation, requiring one or more small fans to compensate. Yes, it can be a juggling act, with little nudges here and there to keep things going well.
FAQs
HOW MUCH LIGHT DO ORCHIDS NEED WHEN GROWN INDOORS?
Orchids require between 12 and 14 hours of light during the summer months, and 12 to 14 during the winter. In areas where natural light is insufficient, florescent or grow-lights can augment the natural light to make up the difference.
There is not difference in light requirements for indoor or outdoor growing.
HOW LONG DO ORCHIDS BLOOM WHEN GROWN INDOORS?
Orchids bloom indoors for an average of a little more than a month. With careful attention and ideal conditions, this period can be stretched out to several months, however, making the extra effort more than worth it for most people.
The species of orchid can make a big difference too, with brief-flowering orchids blooming for just a few weeks, and longer-blooming varieties displaying their flowers for up to two years!
CAN YOU COAX AN ORCHID TO BLOOM MORE THAN ONCE PER YEAR?
Orchids generally bloom once per year, in a natural state, unless they are of a particular variety that blooms twice per year. It is possible to coax near-continual blooming from them though, if the conditions are optimal and you provide them with all that they need. |
Preparing Your Orchids
Step 1 Choose a pot.
1
Choose a pot. Consider using a clear pot to monitor root progress. Three gallon pots work best to allow adequate space for the roots to grow. Make sure the pot has drainage holes so that excess water and mineral buildup can escape.[11]
Choose an orchid pot, which can be found with the terracotta pots at garden shops.
Step 2 Fill each orchid’s pot halfway with a potting medium.
2
Fill each orchid’s pot halfway with a potting medium. Use a material such as moss, bark, coconut fiber, sifted perlite, granular charcoal, cork, or rockwool. The purpose of the potting medium is to hold up the plant. Soil should not be used because it can damage orchids. Buy an orchid potting medium instead at your local gardening store.[12]
Step 3 Plant the orchid.
3
Plant the orchid. Place the orchid on top of the potting medium and fill the rest of the pot with potting medium. Pack firmly around the orchid to keep it in place. The same method works for planting seeds or replanting already-grown orchids.[13]
Step 4 Start with easier orchids.
4
Start with easier orchids. Certain types of orchids are easier to grow. Consider starting out growing Cattleyas, Phalaenopsis, Paphiopedilums, and Cymbidiums. They are beautiful and among the least finicky.
Cattleyas are the standard orchid that most people are familiar with. They like average temperatures around 65-78 degrees Fahrenheit (18.3-25.5 degrees C) during the day and 55-62 degrees Fahrenheit (12.8-16.6 degrees C) at night. They like a lot of light, so west and south facing windows will give them the best light levels.
Part
3
Caring for Your Orchids
Step 1 Pay close attention to your orchids’ progress.
1
Pay close attention to your orchids’ progress. Leaves are a key indicator of the health of your orchids. If they are not getting adequate light, leaves will likely be dark green and will not flower. Additionally, the distance between the leaves will usually increase. If caught early, leaf damage will not necessarily destroy the plant, but serve as an indicator to change conditions.[14]
If your orchids are getting too much light, their leaves will turn a yellow-green or even look reddish. The leaves can even get round sunburn spots if they are overheating.
Step 2 Water when dry.
2
Water when dry. When the potting medium is dry, it is time to water your orchids. They should be checked daily. If leaves appear shriveled, this is another sign that they need more water. Be careful not to overwater orchids. They tolerate being dry better than being drenched.[15]
To prevent overwatering, make sure your pot has adequate drainage holes.
Make sure there aren’t too many dissolved salts in your water and that its pH level is neutral or slightly lower. Sodium should not be greater than 25 ppm.
Quality water is important in caring for your orchids. For best results, mist your orchid daily with bottled, filtered, or distilled water.
Step 3 Apply fertilizer.
3
Apply fertilizer. Consider using a water-soluble fertilizer for best results. The type of fertilizer depends on your type of potting medium. Add fertilizer to the water every three of four waterings. The fourth watering should be fertilizer-free to flush the pot and remove excess mineral buildup from roots.
For bark, use a high nitrogen fertilizer with a 3-1-1 ratio of nitrogen-phosphorus-potassium. Make sure the nitrogen is urea-free because the orchid is not able to use urea-based nitrogen.
For charcoal-perlite or rock, use a 1-1-1 ratio.
Step 4 Clean up the flowering stems.
4
Clean up the flowering stems. When the orchid is done blooming, cut the ends of the stems. This will help them to grow in the future. If you aren’t sure whether it is done blooming, it is best to wait because certain kinds of orchids produce a second crop of flowers.[16]
Step 5 Be aware of the temperature requirements of your orchid choices.
5
Be aware of the temperature requirements of your orchid choices. You will need to know what climate region your type of orchid comes from in order to replicate the right temperature for them. This makes mixing types of orchids a little tricky, so try to stick with one temperature region. Orchids can be roughly divided into three main climate types: cool, intermediate, and warm.
Cool: cool climate orchids are used to minimum winter night temperatures of 45º F (7º C) and a maximum summer's night temperature of 57º F (14º C).
Intermediate: these orchids like a minimum winter night temperature of 50º F (10º C) and a maximum summer's night temperature of 64º F (18º C).
Warm: warm climate orchids like a minimum winter night temperature of 57º F (14º C) and a maximum summer's night temperature of 72º F (22º C).[17]
Step 6 Repot orchids every two years.
6
Repot orchids every two years. The potting medium will break down during this time which will cause the roots to be restricted. Remove the orchid from the pot and remove all potting material from the orchid and root system, as well as any dead roots. Fill your pot halfway with a potting medium, add the plant, and cover with more potting medium. Press the potting medium down firmly so that the plant is securely supported.[18]
f the plant still fits comfortably in the same pot, you can reuse it.
If your orchid has outgrown its pot, it is time to transfer to a larger pot. Try the next size up, but don't go too large or the potting medium will dry too slowly.[19]
Step 7 Prepare greenhouse orchids for new seasonal growth.
7
Prepare greenhouse orchids for new seasonal growth. At the end of the flowering season, orchids go into a resting period during winter/cooler weather months. Keep a resting orchid in full light, dry and un-misted until the first growth shows in spring. Follow any instructions as given for individual orchids as well, which may differ depending on where they have been sourced from. |
Orchids can be classified as warm-growing, intermediate-growing, and cool-growing.
Warm-growing orchids prefer 19°C nights, 21°C days during winter, and up to 27°C days during summer. Intermediate-growing orchids like nighttime temperatures around 13°C and daytime temperatures between 19°C and 30°C depending on the season.
Cool-growing orchids can tolerate as low as 8°C at night during winter and seasonal daytime temperature of 21°C.
During summer, however, these plants’ preference is for 13°C nights and 27°C days.
Given these quite significant differences in temperature requirements, it makes sense to specialize in orchids of the same temperature classification to suit the temperature in your greenhouse, taking into account that a high humidity can sometimes expand the tolerable temperature range slightly. |
Dendrobium is an Orchid.
Growing conditionsDendrobiums are normally grown in shade houses (shade cloth covered structures)or poly houses with good cross ventilation. In high rainfall areas it is advisable togrow in poly houses with shade. Side wall of structures should be covered with shadecloth. The structures are madeto create a congenial environment for crop productionparticularly for protecting the plants from high light intensity, strong winds, excessiverain and pests.
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272 Protected Cultivation and Smart Agriculture3.1 BenchDendrobiumcan be cultivated in pots and kept in the benches to prevent soil bornebiotic agents. Beds can be made on benches. Benches may be made up of ironmeshes, concrete and split bamboo is suitable for cultivation of Dendrobiums. Thepreferable height of the benches is about 2 feet and 6 inches with a width of 3 feet.3.2 Site SelectionThe site suitable for Dendrobium cultivation should be of level topography with theprovision of drainage, wind breaks, sufficient light and aeration and availability ofwater.3.3 Climatic requirementsDendrobiums are mainly tropical, but there are some intermediate and temperatespecies. The most important is requirement of bright light with an intensity requiredfor better growth and flowering is 25 to 30 kilo Lux. But in tropics, a shade is requiredfrom 11am to 3pm because of more light intensity. The shading can be done with25% of sunlight. Optimum light enables growth and quality flowers, however, excesslight may cause brown leaf tips or sunburn symptoms. The temperature requirementsfor Dendrobium range between 15-18 ºC during night and day temperatures between23-29ºC. With the high temperature exposure leaves may become yellow, blotchy,spotted, or may drop off. Humidity is another important factor for Dendrobiums.The humidity between 50 to 75 per cent during the day is quite satisfactory. Properaeration is required for production of quality flowers. Moist atmosphere with goodair circulation is ideal for Dendrobium orchids. Good air movement can be achievedby providing windows or an exhaust fan to green house. Roof and side vents ofconventional open-ventilated greenhouses need to be large enough to get good airmovement.4. Media and PlantingDendrobiums can be grown in wide range of media and it depends on the media forphysical support. They are epiphytic by nature and require porous medium. It shouldprovide good drainage and aeration. Media should be reasonably stable. Selectionof media also largely depends on growing conditions. It can be prepared from thelocally available materials like coconut husk, brick bits, and pieces of tree bark,stone chips and charcoal pieces. The plants with fine roots require small or mediumsized ingredients of around 3-4 cm. These materials generally increase the aeration,porosity and drainage and decrease the water holding capacity of the media. Theoptimum pH of 5.0 and EC of 0.6 mS/cm for media and it should be sterilized by 4%formaldehyde solution to prevent the diseases. The coconut husk needs to be washed4 to 5 times to leach out the excess sodium.
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Growing of Dendrobium Orchids in Greenhouse 2734.1 ContainersDendrobiums are epiphytes; it can be grown in several types of containers such asplastic pots, earthen pots, wooden baskets, coconut husks, tree fern rafts, wood piecesetc. (Fig. 1). It can be grown even in coconut shell as a potted plant for outdoordecoration. Commercial cultivation can be feasible in different sizes of plastic orearthen pots. Polythene bags can also be used for the cultivation of Dendrobiums.Pots with necessary holes on the sides and bottom regulate good drainage.4.2 PlantingDendrobiums can be planted in plastic pots, polythene bags and earthen pots. Largeholes to the sides of pots should be kept to ensure good drainage and aeration.Orchids can be planted into beds of medium instead of individual containers. Plantingdistance depends on the spacing of bed, length and width of the structure, size of thebags, and pots, life span of the plant and plant density. Generally, 50-60 thousandplants/ha are being accommodated.4.3 PottingDendrobium plants should be planted in the corner that is at one side of the pot toensure better growth by providing space for producing new canes. The procedure forpotting orchid is instead of centering the plant; the older portion of the plant shouldbe as close to one edge of the pot, leaving room on the opposite side of the pot forthe new growth. The base of the plant or the rhizome should be just a little higherthan the potting media so that leaves do not touch the media and the top of the rootsare just a little bit exposed.4.4 Repotting and care after repottingRepotting is done after 2-3 years if the plants have over grown the pots. The oldroots and leaves can be pruned. Plants can be divided with a minimum of 3-4 shootsand a sprouted bud. Repotting should be done after the flowering period. Repottingis done using a fresh media. Repotting is a shock to plants. For 3 to 4 weeks thenewly repotted plants must be placed at a location where they will be getting lesslight than what they usually get. The lower light levels will reduce the stress causedby the repotting shock and will help the plants to recover better and faster. Waterlightly (just enough to get the potting material moist, not enough for the water to runthrough the drainage holes) until a week after repotting.5. IrrigationAs the growing media are porous and hold little water plants should be irrigatedfrwquently and the frequency of irrigation greatly depends on season, weather andplant growth. When the new growth begins in the spring, the Dendrobium orchidlikes to have an increase in water and fertilizer. Media must be dried out between
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274 Protected Cultivation and Smart Agriculturewaterings. In dry season, frequent irrigation is needed by once in a day. But in humid,cooler areas irrigation may be done once to three times per week. Under wateringcauses shriveling of the leaves and canes, drying of root tips and stunted growth.Over watering invites root diseases and partial yellowing of leaves. Application ofwater through overhead sprinkler encourages the foliar diseases. It is advisable toapply water to the root zone.6. Quality of WaterFor providing irrigation to Dendrobium orchids, the water should be neutral and non-saline. If rain water is used and as rain water is slightly acidic, pH of around 5.6 issuitable. The temperature of water should be normal (room temperature).7. Nutrient ManagementNutrient management is an essential aspect for flowing and quality of flowers. Flowerquality can be improved by by proper nutrient management. The high concentrationof phosphatic fertilizer, such as 10:20:20 facilitates the blooming in Dendrobiumorchids.7.1 Growth phase: First year (for growth of young plant)1. 20:10: 10 NPK @ 0.1% (1g/L water) - Foliar application at 15 days interval.2. Calcium nitrate @ 0.05%; Magnesium sulphate @ 0.1 %; Micronutrient (Ferroussulphate: 50 ppm Fe, Boric acid: 50 ppm B, Zinc sulphate: 50 ppm Zn) foliarspray at bimonthly interval.7.2 Flowering phase: 2nd year onwards7.2.1 February to May (for flowering)1. 10:20:20 NPK (@ 2g/L water) foliar application at monthly interval.2. Calcium nitrate @ 0.05% (0.5g/L water) foliar application at monthly interval.3. Magnesium sulphate @ 0.1 % (1g/L water) foliar application at monthly interval.4. Micronutrient (Ferrous sulphate: 50ppm Fe (0.25g/L), Boric acid: 50 ppm B(0.28g/L water), Zinc sulphate: 50 ppm Zn (0.22g/L water) foliar application atmonthly interval.7.2.2 June to September (for vegetative growth)1. 20: 10: 10 NPK @ 0.2% (2g/litre of water) - Foliar application at 15 days interval.2. Calcium nitrate @ 0.05% (0.5g/ litre of water ) - foliar application at monthlyinterval.3. Magnesium sulphate @ 0.1 % (1g/ litre of water) - foliar application at monthlyinterval.
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Growing of Dendrobium Orchids in Greenhouse 2754. Micronutrient [Ferrous sulphate-50ppm Fe (0.25g/ litre of water ), Boric acid-50ppm B (0.28g/ litre of water ), Zinc sulphate-50 ppm Zn (0.22g/litre of water )]foliar application at monthly interval.7.2.3 October to January (for vegetative growth and flower bud initiation)1. 20: 20: 20 NPK @ 0.2 % (2g/L water) foliar application at monthly interval.8. Growth Regulator ApplicationFoliar application of 50 ppm BA increases the growth and flowering. GA3 and BAcan be given in combination; it reduces the adverse effect of the BA. Application ofGA3 50 ppm and 100 ppm increases the spike length. Drenching the roots with 50ppm BA solution enhances vegetative growth as well as flowering.Fig. 2: Flowering Dendrobium plants and flower packaging9. Harvesting and post-harvest careFlower spikes are generally harvested with four to six unopened buds when 70-75%of the lower flowers fully open (Fig. 2). Flowers are harvested in the early morningor late evening by a sharp and sterilized knife. Harvested flowers are placed in cleanwater with the cut ends submerged about 2-3 inches. Immersing the spikes in warmwater at 55 0C for 5 seconds extends the post- harvest longevity of flowers. Pre-cooling at 4-6 0 C for 3- 4 hours and pulsing improves the vase life. Then the spikesare taken in the cool shaded packing area. In order to improve the quality and vaselife of flowers spikes, the cut spikes should be subjected to pulsing with sucrose atthe rate of 2-6% for 2- 4 hours. Sucrose in keeping solutions as a carbon sourcemay extend the vase-life of cut orchid flowers. The best pulsing treatment is sucrose6 % and BA 25 ppm. A combination of biocide, sugar and hormone (8-HQC 100ppm + sucrose 2 % + BA 25 ppm) remarkably enhances the post-harvest life of theDendrobium cut flowers.
(PDF) Growing of Dendrobium Orchids in Greenhouse. Available from: https://www.researchgate.net/publication/347239849_Growing_of_Dendrobium_Orchids_in_Greenhouse [accessed Apr 11 2024].
10. YieldFlower production of Dendrobium starts from 18 months after planting. It can produce5-6 spikes per plant per year. The number of flower spikes per plant increases asplants age, reaching a maximum at 3-4 years and then decline. Spike length reachesa maximum after 3 years.11. ConclusionDendrobiums are attractive orchids can be grown in wide range of climatic conditionsand by adoption of proper technologies the orchids can be grown in tropical andsub-tropical environments. For successful raising of Dendrobiums congenialenvironmental condition may be created to minimize climatic adversities. Further,with adoption of suitable package of practices and intensive management the orchidsbloom with quality flower which indicate commercial viability of cut-flower.
(PDF) Growing of Dendrobium Orchids in Greenhouse. Available from: https://www.researchgate.net/publication/347239849_Growing_of_Dendrobium_Orchids_in_Greenhouse [accessed Apr 11 2024]. |
Orchids are fascinating plants that often have specific requirements for optimal growth, including soil pH. Generally, orchids prefer slightly acidic to neutral soil conditions, with a pH range of around 5.5 to 6.5 being ideal. However, it's important to note that many orchids are epiphytes, meaning they grow on trees or rocks in their natural habitats, rather than in soil. As a result, they have adapted to different growing mediums, such as bark, moss, or specialized orchid potting mixes.
When growing orchids in a greenhouse, it's crucial to replicate their natural growing conditions as closely as possible. This includes providing a well-draining medium that allows for good air circulation around the roots. Orchid potting mixes, often composed of materials like bark, perlite, and charcoal, provide excellent drainage and aeration for orchid roots. |
Orchids generally thrive in environments with moderate to high humidity levels, typically ranging from 50% to 80%. However, the specific humidity requirements can vary depending on the orchid species and their natural habitat. For example, orchids native to rainforests may prefer higher humidity levels compared to those originating from drier environments.
In a greenhouse setting, maintaining humidity within the optimal range can be achieved through several methods:
Humidity Trays: Placing trays filled with water and pebbles beneath orchid pots can increase humidity levels through evaporation. This is especially useful in drier environments.
Misting: Spraying the air around orchids with water can temporarily increase humidity. However, misting should be done carefully to avoid water accumulating on the orchid leaves, which can lead to fungal or bacterial issues.
Humidifiers: Using a humidifier in the greenhouse can help maintain consistent humidity levels, especially during periods of low humidity or in regions with dry climates.
Proper Ventilation: While high humidity is beneficial for orchids, it's also essential to provide adequate ventilation to prevent the growth of mold and fungal diseases. Proper air circulation helps maintain healthy plants and reduces the risk of humidity-related issues.
Grouping Plants: Clustering orchids together can create a microclimate with higher humidity levels, as plants release moisture through transpiration.
Mulching: Applying a layer of mulch to the top of the potting mix can help retain moisture and increase humidity around the orchid roots.
By monitoring humidity levels and adjusting environmental conditions accordingly, you can create an optimal growing environment for your orchids in the greenhouse, promoting healthy growth and flowering. |
Plant Care
Planting
Pruning and Training
Guide Start
Section 5 of 8
Temperature and humidity
Sweet peppers can cope with a minimum night temperature of 12°C, but will grow better if kept above 15°C. But they don't like to be too hot – temperatures over 30°C can reduce fruiting, so keep the greenhouse well ventilated and put up shading in summer.
Peppers also like humidity, so add moisture to the air in warm weather by ‘damping down’ the greenhouse regularly – pour a full watering can over the floor, leaving it to evaporate during the heat of the day.
Watering
Water regularly to keep the potting
Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.
compost or soil evenly moist, ensuring plants neither dry out nor get waterlogged. They may shed their flower buds if they run short of water. Also apply mulch to damp soil to help retain moisture around the roots. Plants in containers may need watering daily in summer, as the compost will dry out quickly.
Feeding
To encourage fruiting, feed sweet pepper plants once a week with a high-potassium liquid fertiliser, once flowering starts.
Related RHS Guides
Choosing fertilisersLooking after plants in potsGrowing veg in pots
6
Pruning and Training
Plant Care
Harvesting
Guide Start
Section 6 of 8
Pinch out the tip of the main stem when plants reach about 30cm (1ft) tall, to encourage side-shoots to form, which should lead to more fruit. You can also
Removal of a plant’s growing tip (usually with finger and thumb) to encourage it to produce side-shoots, forming a bushier, well-shaped plant that will bear more flowers and/or fruits.
pinch out the tips of the resulting side-shoots if you want more but smaller fruits.
Support each plant with a sturdy bamboo cane, tying in the main stem as it grows. If plants produce a heavy crop of large peppers, more support may be needed as the stems can be quite brittle and snap easily. Insert bamboo canes around the plant and attach the fruit-laden side-shoots using soft twine.
7
Harvesting
Pruning and Training
Problems
Guide Start
Section 7 of 8
Harvest sweet peppers regularly, to encourage further fruiting
In a greenhouse, sweet peppers can be harvested from mid-summer into autumn. Outdoors, they will start fruiting later, usually in August, and finish earlier, once temperatures start to drop in late summer or early autumn. Pick as required when the fruits are swollen and glossy. Most sweet peppers ripen from green to red, but some varieties turn yellow, orange or purple. The fruits get sweeter as they ripen. You can harvest your peppers at whichever colour and stage of maturity you prefer, but bear in mind that leaving fruits on the plant to ripen fully will hinder further fruit development. Towards the end of the season, cover outdoor plants with
Transparent fleece and other floating films, known collectively as crop covers, are laid over or around plants hastening their growth, and protecting against weather and pests. They are usually used without supporting hoops.
fleece or bring potted plants indoors, to help the remaining fruits ripen. You can use grow lights to extend the cropping season indoors – see our video guide below for tips. |
Watering Peppers
Peppers are a crisp, vibrant vegetable and they need a lot of water to get that way. Soil should be kept moist at all times, and daily watering is a good idea at the height of the summer, when days are long and hot. An inch or so of water every four days is the general rule.
Soil for Peppers in a Greenhouse
Peppers love rich soil with enough calcium and phosphorous. Ideal pH is between 7.0 and 7.0. Ideal soil temperatures hover around 21°C. Add some fertiliser as soon as first fruits appear, but don’t overdo it or the plant will not produce adequate fruit at all.
Heat and Light
Peppers like consistent light in the right temperature. About 6 hours of light a day, or more, is enough. Temperatures should be between 25 – 28°C in the daytime, and nighttime greenhouse temperature should be around 16-18°C. Below 10°C – 12°C or over 35°C and you’ll risk losing your plants altogether. Humidity should be around 65-85% for optimal growth.
Humidity
High humidity levels will cause a drop in pollen release and reduce the crop amounts. Low humidity may dry out the pollen and prevent germination. Optimal humidity will allow pollen to be produced and to release properly for successful germination.
Harvesting grown peppers
It is best to harvest peppers using scissors, a sharp knife, or similar tool, to prevent the more delicate parts of the plant from breaking when you pull on the peppers themselves. Also be mindful not to rub your face or eyes when harvesting peppers, as the chemicals that make them hot and tangy can be very irritating to skin and eyes, especially when it comes to the hotter peppers. |
What Is the Ideal Temperature for Greenhouse Pepper Production?
The most basic function of any greenhouse is to keep the right temperature for the crops. This is the reason early greenhouses were developed, and is still relevant today.
Plants perform their physiological functions most efficiently in their preferred temperature range. This includes photosynthesis and nutrient uptake and processing.
When temperatures are too high, or too low, the plants experience stress. Stress slows down vegetative growth and fruit development, leading to less and smaller fruit. Nonoptimal temperatures also make plants and fruit more susceptible to diseases.
Pepper crops can grow in a relatively wide temperature range. However, the ideal temperature range to optimize growth and fruit production is around 18-26°C.
In nature plants experience a natural day-night cycle that includes lower nighttime temperatures. In the case of peppers, the ideal daytime temperature is 21-26°C. The ideal nighttime temperature is 18-21°C. Of course, these ranges may vary, depending on the pepper varieties you grow.
Pepper plants may still grow outside of the ideal temperature range. They can go as low as 15°C and as high as 32°C. Going over or under this range may result in blossom drop – a common issue pepper growers work hard to avoid.
When it comes to germinating pepper seeds, growers usually achieve the best results with a soil temperature of 23-29°C. You can maintain warmth for your pepper seedlings using a heat mat, or other local heating equipment.
Ideal Temperatures for Pepper Cultivation:
Daytime – 21-26°C
Nighttime – 18-21°C
Seed germination – 23-29°C
How to Create Optimal Greenhouse Temperatures for Peppers
Every greenhouse has its own temperature control system, depending on the greenhouse’s type, build, local climate, and weather patterns. As peppers enjoy warm weather, greenhouses typically require more heating than cooling.
Some of the most common ways to heat a greenhouse include heating pipes running boiling water, heat pumps, HVAC, etc.
What Is the Ideal Humidity for Greenhouse Pepper Production?
Humidity is one of the biggest climate factors in any greenhouse. Like temperature, it has a major impact on growth, fruit development, plant health, and overall yield size and quality. So in order to maximize your pepper cultivation, it’s important to maintain the right relative humidity or VPD range.
When relative humidity is too high or low, pepper plants won’t be able to effectively take in nutrients or photosynthesize effectively.
How Relative Humidity Impacts Nutrient Uptake and Photosynthesis
In high humidity, plants lose their ability to transpire water vapor, because the air is already too saturated. Transpiration is a crucial part of a plant’s process. It’s what allows it to take in water and nutrients from the soil. So, high humidity stunts growth and development.
In a low relative humidity environment pepper plants face a different struggle. The lack of water vapor in the air leads to excessive transpiration. The plants recognize this and counteract by closing their stomata, the small pores that release water vapor and absorb radiation.
This is known as water stress. So, low humidity also slows down the plants’ growth and development.
High Relative Humidity Leads to Diseases and Molds
Humidity control doesn’t just optimize pepper development, but the plants’ health as well. When the environment is too moist or wet, which is a result of high humidity, diseases and molds may take hold.
Some of the most common pepper diseases, such as blight, leaf spot, and even fruit splitting, only occur in high humidity. Maintaining ideal relative humidity levels helps avoid these issues, significantly reducing yield loss and improving the overall produce quality.
The optimal relative humidity level for pepper greenhouses is generally 65-85% RH. In terms of vapor pressure, the ideal VPD for peppers is around 0.5-1.0 kPa. In later stages, when the plant is producing fruit, VPD levels should be higher than during vegetative growth.
Humidity also affects pollination, so it’s very important to keep an eye on relative humidity to maximize fruit development. High humidity often reduces the amount of pollen flowers produce, while low humidity may dry the pollen, preventing germination.
Ideal Relative Humidity & VPD for Pepper Cultivation:
RH – 65-85% RH
VPD – 0.5-1.0 kPa
How to Maintain Optimal Humidity in Pepper Greenhouses
Like all plants, pepper crops evaporate water. In an uncontrolled greenhouse, or any closed environment, high humidity is inevitable. In such an environment, it’s critical to actively control humidity.
In order to completely control humidity, it’s important to understand what affects it. First, relative humidity is relative to temperature. Warm air can hold more water vapor than cool air. So as temperatures drop, relative humidity rises, even if the absolute amount of moisture remains the same.
There are additional factors that affect humidity. Lighting and airflow, for example, increase the plants’ transpiration rate. Most commercial greenhouses house a lot of plants which evaporate a lot of water. So, in most cases, growers need to reduce humidity, rather than increase it.
The main traditional method to so is heating and venting. Greenhouse operators open windows and vents in order to let the moisture out. However, this also releases heat from the greenhouse, so they must reheat constantly, to make up for the heat loss.
Heating and venting is still an effective and even efficient method, under certain circumstances. During the day, if the weather is suitable, it can be a great way to easily reduce humidity. However, overnight, or when it’s rainy, damp, or cold, growers often won’t see positive results. In these cases, they may remain with high humidity as well as high heating costs.
The only method that’s sure to provide full coverage, in any weather, is active dehumidification. Dehumidifiers that are designed for horticultural settings ensure complete humidity control at the highest energy efficiency rate. Over the past decade, growers that use DryGair report an average of 50% energy savings.
Using Air Circulation to Improve Humidity Control
Any commercial greenhouse or grow room utilizes some form of airflow. Blowing air through the plants and foliage helps disperse trapped moisture, known as microclimates. This is an important part of humidity control and helps stimulate plant activity as well.
There are various types of airflow, including vertical fans, horizontal fans, and of course, air circulation.
Air circulation is a specific type of air movement, in which the air circulates uniformly throughout the entire space. Its benefit is in ensuring that the air reaches all parts of the greenhouse equally, creating uniform conditions everywhere. This doesn’t just assist in disease prevention, but also in produce consistency.
All DryGair dehumidifiers include a patented air circulation module that disperses the treated air in all directions at once – 360°.
Proper humidity control prevents diseases and maximizes plant growth and development. But it also allows growers to house more plants in the same space. By reducing humidity buildup between plants, you can safely allow for higher plant density and more crowded foliage.
Additional Tips for Greenhouse Pepper Cultivation
Climate control plays a major role in growing and harvesting peppers in a controlled environment. However, there are additional steps you can take to improve cultivation, increase yields and quality, prevent diseases, and reduce energy costs.
Keep Your Pepper Greenhouse Dry
Many of the most common and detrimental diseases for peppers develop in wet environments. So keeping your greenhouse surfaces, as well as plants dry is a surefire way to prevent these issues.
The two main ways in which water appears in a greenhouse are through irrigation and humidity. Fortunately, you can control both. We’ve already covered how to effectively control humidity in the previous section of this guide.
When it comes to irrigation, it’s best to water your pepper plants straight to the potting mix or soil. Watering this way prevents water from coming into contact with the plants. This may seem too simple, but it’s highly effective in preventing mildews and other fungal diseases.
Use Thermal Screens to Insulate the Greenhouse
Growing greenhouse peppers can be energy intensive. The colder your climate is, the higher your energy costs are likely to be. However, there are ways in which you can reduce your energy requirements and cut costs significantly.
Deploying thermal screens is a highly effective way to reduce heat loss, and therefore heating. Heating is one of the biggest energy expenses in a greenhouse, so this can make a big difference. You can install two or even three screens to increase the effectiveness and reduce heat loss even more.
Traditionally, keeping the greenhouse sealed off completely would pose problems. Keeping heat inside was a benefit but would often lead to high humidity. However, by following this guide and utilizing dedicated dehumidifiers to deal with humidity from inside, that’s no longer an issue. |
High-yielding greenhouse peppers
By Andrew Mefferd
February 1, 2015
In this second of two articles looking at less popular but lucrative greenhouse/hoophouse crops, we will look at the particularities of growing peppers in protected culture. As I mentioned in last month’s article about growing greenhouse eggplant, if you have grown greenhouse tomatoes, many of the techniques you already know can be applied to this solanaceous crop. There are just a few differing techniques that can help you get the most out of your greenhouse pepper crop.
Ripe, colored greenhouse bell peppers are not as productive a crop as greenhouse tomatoes, so you will have to get a higher price per pound for peppers to make a profit. On the other hand, peppers are a much slower growing crop so you will not have to invest quite as much labor to the same area of peppers as you would in tomatoes.
The difference between growing peppers in the field and in protected culture is much like the difference between determinate and indeterminate tomatoes. In the shorter field season, pepper plants are pruned minimally or not at all and allowed to develop as many fruits and side shoots as possible to form a bush plant habit, much like a determinate tomato. In protected culture, plants are encouraged to grow up and set a controlled amount of fruit, more like a pruned indeterminate tomato. The tall plants take advantage of all the vertical space in the greenhouse, and the fruit pruning keeps the plant productive over a very long season by always keeping the fruit load balanced with the amount of plant that is available to support it.
Starting seeds
The most important thing that needs to be understood if you are used to growing tomatoes or eggplant is that peppers are a much less vigorous, slower growing crop than the other solanaceous crops. This must be taken into account from the very beginning. Whereas some growers take as little as six weeks to go from seeding to setting transplants in the greenhouse for tomatoes and eggplant, two months is typical for developing a transplant-ready pepper plant. They even germinate somewhat slowly, with emergence generally taking place 3-4 days after seeding.
peppers
Peppers growing in a high-tech greenhouse in Canada last June were on track to hit 17 feet by the end of the season. Photo by Andrew Mefferd.
To get good germination, seeds must be held at 27-32°C constantly from the time of planting until germination. Peppers can be somewhat finicky germinators, and most of the problems I have seen with germination come from not getting the temperature up high enough in the first place and then keeping it up. Using bottom heat from a thermostat-controlled heat mat or a germination chamber are the best ways to get constant heat at precisely the right temperature. Just putting seeds out in a warm greenhouse is not enough to ensure good germination. Dropping nighttime temperatures ensure seeds spend a lot of time at sub-optimal temperatures.
Even if you are using heat mats or a chamber, it is important to have a thermometer with the probe monitoring the temperature at the depth where the seed is in the soil. Merely setting the thermostat to the desired temperature is not enough. Thermostats that have gone out of calibration, air leaks, and unexpected heat buildup are all common factors that may cause the temperature to go too low or too high.
Varieties
The weaker nature of the pepper plant must also be taken into account when deciding on which varieties to use in your growing situation. The breeding work in greenhouse peppers focuses on producing a plant habit that is conducive to growing up rather than branching out. In practical terms this means a pepper plant that has more distance between internodes (taller) and a very even growth habit, producing two evenly matched branches at every node. The contrasting habit observed in field varieties is less distance between nodes (shorter), and a less regular branching habit, sometimes producing more than two branches per node with varying levels of vigor. It is desirable to have two evenly matched branches formed at every node. That way if one branch is damaged, you always have a backup you can use if they are all evenly matched. The other main adaptation of greenhouse peppers is resistance to checking under greenhouse conditions. Field varieties grown in greenhouses may develop checking (cracking) on the surface, similar to what is sometimes seen in jalapeno peppers.
High-yielding-greenhouse-peppers
Greenhouse peppers are broken into two major groups, with varieties suited to high-tech or low-tech greenhouse growing. Each group has characteristics that will help it thrive in the particular conditions of the environment that it was bred for.
Yields and quality are maximized in high-tech greenhouses by growing the plants very fast using high temperature, optimizing fertility and eliminating as much stress as possible. The speed of growth corresponds to the temperature in the greenhouse — the hotter the faster. High-tech greenhouses use a lot of environmental control technology to essentially create pepper heaven.
However, high heat and fertility and low stress tend to have a vegetative effect on plants, causing them to focus on leaf and stem growth at the expense of fruiting growth (for more on this, see the article I wrote about vegetative/generative steering of greenhouse crops in the June 2013 GFM). Since it is expected that they will be grown in a vegetative environment, peppers bred for high-tech greenhouses are selected to be generative, and focus more on fruiting growth, than those bred for low-tech greenhouses. The idea is that you put a naturally generative variety into the vegetative high-tech greenhouse environment and end up with a balanced plant.
The greenhouse environments that we refer to as low-tech could encompass anything from a simple greenhouse like a high tunnel with a heater installed, and even to high tunnels in warm areas, like parts of the west coast and southwest United States. What we are not talking about is high tunnels in cold areas of the country. If you live in a shorter season area (most of the northern half of the U.S.), your season likely isn’t long enough and temperatures not high enough to take full advantage of the benefits of the greenhouse pepper varieties, even in a high tunnel. In cold areas without heat, you are probably better off growing field varieties with field techniques, even in a high tunnel.
The characteristics that low-tech greenhouse environments have in common are less sophisticated climate control technology, meaning that temperatures are more likely to get too high during the day and lower than ideal at night. Fertility may also be less optimized and other stresses may be more present than in fancier greenhouses because there is less control over the environment. Temperature, fertility, and other growing conditions that are less than optimal all add up to one thing: plant stress. And one of the major effects of stress on a plant is to reduce the vigor of the plant.
Varieties intended for low-tech greenhouses are higher in vigor than varieties bred for high-tech greenhouses. Peppers tend to be slow-growing, generative plants by nature. Generative varieties grown under more stressful conditions (like a low-tech greenhouse) run the risk of losing too much vigor and stalling out. Vigorous varieties bred for low-tech greenhouses will hopefully remain balanced grown in the more generative environment.
The way a variety is bred and slotted is the best way to choose a variety that will thrive under your conditions. Low-tech varieties run the risk of getting too vegetative in a high-tech, bells-and-whistles kind of greenhouse environment. And high-tech varieties may get too weak when their vigor is sapped by more stressful conditions tin a low-tech greenhouse environment. That said, the slotting is not so rigid that varieties don’t sometimes perform well outside their intended environment. It is worth trialing small numbers of a few different varieties in your greenhouse to see what really performs the best for you.
A Johnny’s, we looked at 24 varieties bred for greenhouse production and chose to offer these: For high-tech greenhouses: Felicitas, Orangela, and Bentley. For low-tech: Sprinter,Sympathy, and Moonset.
Propagation and transplanting
Greenhouse peppers are propagated in much the same way as greenhouse eggplant. Refer to the article in last month’s GFM for seeding and medium recommendations. Once you have a seedling, grow at a daytime temperature of 21-23°C and nighttime temperature of 20°C. Since peppers spend a relatively long time as seedlings before they are transplanted, it is important that they receive supplemental fertility and not just water. Fertilize with a complete nutrient solution, with an EC of 1.5-2 and a pH of 5.2 or the equivalent to keep the plants green and healthy. When first transplanting into the greenhouse, maintain a flatter than usual temperature profile of 23°C during the day and 21°C at night. Use this temperature regime for the first week to promote rapid vegetative growth and rooting in.
As with any greenhouse crop, if you are growing in soil, make sure to get the saturated media extract soil test instead of a standard field soil test. This test takes into account the greater amount of fertility necessary over the long greenhouse season, and will show your fertility needs much better. If you are growing hydroponically, consult your fertilizer supplier about a program suitable for optimizing greenhouse pepper growth.
Greenhouse pepper plants may be grown with two or four heads per plant. Two heads will result in larger peppers, and plants may be able to bounce back from stressful conditions more quickly since there is less demand on each root system. Two heads is most common here in North America because the American market is for large bell peppers. Four heads is common in Holland, where large peppers are not as important. In areas with very hot summertime temperatures, use two heads per plant for resilience.
When it comes time to transplant, lay out the rows so that you can accommodate 6-7 stems per square meter (a square meter equals nine square feet). The most common way to achieve this packed planting density is to use a double row of plants, with approximately a foot between plants and six inches between stems. Use the same stem spacing for two or four-headed plants, simply using half as many plants with four-headed plants. You can increase the spacing between stems if you want to reduce planting density.
Stems are anchored to two overhead wires two feet apart, with a walkway three feet wide. This two foot wide double row with a three foot wide walkway is a common way to set up greenhouses, since this wire spacing can accommodate the common spacings of all the commonly grown greenhouse vining crops- tomatoes, cukes, eggplant and peppers. With this greenhouse setup you can change crops without having to change your trellising. For more on this greenhouse spacing, see my article on hoophouse improvements from the April 2013 GFM.
Growing
After the first week in the greenhouse, lower the nighttime temperature to 18-20°C, and maintain daytime temperatures as close to 23-24°C as possible. Peppers have difficulty setting fruit at nighttime temperatures above 20°C, so it is important that temperatures at least come down that low at night. Cooler nighttime temperatures will result in a more generative plant, warmer nights will encourage vegetative growth. Though it will be impossible to maintain daytime temperatures that low in most areas during the summer, the takeaway is that pepper plants don’t actually need it that hot to thrive. This is also important to keep in mind in hot areas, that if pepper growth suffers during the summertime it may be due to the plants getting too hot. Some growers try to help their peppers through the excessively hot parts of the summer by whitewashing or applying shade cloth to the greenhouse. |
GROWING SWEET PEPPERS IN A GREENHOUSE
Sweet peppers, also known as bell peppers, are the ones you’ll typically find in the salad aisle of the supermarket. Mild and sweet (it’s in the name, after all), they’re great for cooking or eating raw, and come in a variety of colours.
Sweet peppers originate from South American countries, so you won’t be surprised to hear that they love hot, sunny conditions. That’s why greenhouses provide the perfect growing conditions.
Here are our tips for getting the most out of yours:
Sow them anywhere between mid-February and early April in plenty of good compost to help with water retention. You can either sow them in individual pots or in trays, spaced roughly 18 inches apart.
Place your peppers somewhere in the greenhouse that will get at least six hours of sunlight a day.
Keep the soil consistently wet, as peppers require lots of water – particularly in warmer conditions. A good rule of thumb is to give them at least an inch of water every four days or so, more regularly if the weather is hot.
Feed with a high potash liquid fertiliser at half strength with every watering, roughly three weeks on from planting.
Harvest when they look ready! You can do so when they’re ripe and still green or wait until they’ve gained their full colour.
HOW TO GROW CHILLI PEPPERS IN A GREENHOUSE
Chilli peppers tend to grow quite slowly, and they require a good amount of light and warmth – again, making them perfect for greenhouse conditions. Be sure to choose a variety that suits your tastes in terms of spice – after all, you want to be able to enjoy what you’ve grown!
Here are our tips for growing the best possible crop:
Plant your chillies early in the season, around January or February if you can. They need plenty of bright sunlight so make sure they’re in a good position.
Sow seeds either in individual pots or 15 to a tray.
The spicier the pepper, the longer the maturing period. Chilli peppers require a longer germination period than other types of pepper, however you can speed up the process by soaking for seeds before planting. Doing so for 10 minutes will help to reduce germination time.
Once your plants have a healthy root system, transplant them into their final place – either pots or a standard grow-bag.
If left for long enough, chillies will dry and shrivel on the plant. You can also pick them and leave them to dry in an airing cupboard – a great way to get chilli flakes for use in cooking.
THINGS TO WATCH OUT FOR
When it comes to growing peppers in a greenhouse, there are a few things you’ll need to keep an eye on to prevent anything that could harm the growth of your crops.
Pests such as aphids and flea beetles can prove a pain, but are easily tackled using the hose. Flea beetles tend to appear around midday, and will soon disappear when faced with some drizzle! Aphids require a bit more force, so give them a powerful blast (while being careful not to soak or damage your peppers). You could also use sticky yellow cards.
So there you have it, our guidelines for growing peppers in a greenhouse! Whether you prefer sweet or spicy, get growing and enjoy!
Looking for advice on growing other vegetables in your greenhouse? We’ve got plenty more helpful guides like this one, including how to grow cucumbers in a greenhouse and how to grow sweetcorn. Just head on over to our blog to see loads of tips and advice to help your greenhouse flourish. |
Greenhouse Peppers - Key Growing InformationGreenhouse peppers, grown on hanging trellises in our greenhouse trials.
SCIENTIFIC NAME:
Capsicum annuum
CULTURE:
Sow seeds in desired medium 6–8 weeks prior to transplanting. Maintain a constant 27–32°C soil temperature. When first true leaves just show, transplant the seedlings into cell-type containers or blocks. 2" or larger containers will produce larger, stronger root systems; 4" blocks are the standard. Grow plants at 21–23°C days and 20°C nights. Fertilize with a complete nutrient solution (EC 1.5–2, pH 5.2) or equivalent as needed to keep plants dark green and healthy. When transplanting into the greenhouse, try to maintain temperatures of 23°C during the day and 21°C during the night for the first week to promote rapid vegetative growth and root establishment. 7–10 days after transplanting into the greenhouse, lower night temperatures to 18–20°C and keep a daytime temperature of 21–24°C. For two-stemmed plants, use a plant density of 3–3 1/2 plants/square meter, which results in 6–7 stems/square meter (9 sq.ft.). Plants can be pruned to 4 stems, maintaining 6–7 stems/square meter (9 sq.ft.), but fruit will be smaller. Remove flowers up to the second or third node after initial branching to allow the plant to reach a suitable size before trying to support a fruit load.
TRELLISING:
We recommend pruning the plants to 2–4 stems and trellising them up a string, like greenhouse tomatoes.
HARVEST:
Harvest peppers when they are 80% or more final ripe color.
DISEASES AND PESTS:
Use crop rotation or new media to reduce soilborne disease problems. Use regularly scheduled releases of beneficial insects to control pests.
DAYS TO MATURITY:
From transplanting.
SEED SPECS:
SEEDS/OZ.: 3,200-4,150 (avg. 3,700) |
How to grow peppers
Cultivating sweet bell peppers
To ensure a good, reliable crop, peppers need a warm, sunny position outside, or they can be grown in a greenhouse, grow frame or similar covered structure. Although they can be grown in well-prepared, rich, moisture-retentive soil, they usually crop better and more reliably if grown in containers.
Pepper varieties
The following are all good, reliable varieties: Ace, Bell Boy, California Wonder, Gypsy, Mohawk, Redskin.
Sweet peppers growing, ready to harvest
Sowing peppers
For greenhouse growing, you can sow from mid-February to early April. For growing outdoors, sow in mid- to late March.
Sow seeds at 18-21°C in pots of good seed sowing compost. Transplant the seedlings individually into 9-10cm (3-4in) pots when two true leaves have formed, and grow them on at around 16-18°C.
Gradually harden off the sweet pepper plants for 10-14 days before planting outside.
How to care for peppers
Plants are ready to put into their permanent cropping position once the roots fill the 9-10cm pots.
Pot them up into 23-25cm (9-10in) pots of good compost in late April (if growing in a heated greenhouse), mid-May (unheated greenhouse) or late May/early June if growing outside. They can also be grown in growing-bags, but will need very careful watering. Support them with bamboo canes or similar and tie them in as they grow.
Pinch out the growing tip when plants reach about 20cm (8in) high to encourage bushy growth and better cropping.
Water regularly and feed with a balanced general feed, switching to a high potash feed when the first fruit has set.
Mist the foliage regularly, especially under cover, with tepid water to discourage red spider mite and to improve flower set and cropping.
Harvesting peppers
Pick the fruit as needed when it has reached a good size, is green, swollen and glossy. Or you can keep the fruit on the plant to change colour, but this may reduce the overall crop.
Flowering season(s) - Spring, Summer,
Foliage season(s) - Spring, Summer, Autumn,
Sunlight - Full sun,
Soil type - Clay, Loamy, Sandy,
Soil pH - Neutral,
Soil moisture - Moist but well-drained,
Ultimate height - Up to 90cm (3ft),
Ultimate spread - Up to 60cm (2ft),
Time to ultimate height - 6 months. |
Greenhouse Growing: Bell Peppers
Growing bell pepper plants from seed in a greenhouse can be a rewarding and cost-effective way to produce a bounty of sweet and spicy peppers that can be used as starters, in salads, or in cooking. If you're looking to grow sweet peppers from seed this season, read our handy guide for simple yet effective grow your own practices.
Popular Homegrown Bell Pepper Varieties
There are many varieties of bell pepper plants that can be grown from seed, and each has its own unique flavour and characteristics. Here are some of the most popular bell pepper varieties that are suitable for growing from seed in the UK:
California Wonder
This is a classic bell pepper variety that is known for its sweet, mild flavour and thick-walled, blocky fruits. California wonder peppers are a medium to large size and turn from green to red when ripe. They are popular for both fresh eating and to use in cooking.
King of the North
Similar to California wonder but a little shorter in size, these are a medium to large bell pepper variety known for its sweet, juicy flavour and thin walls. King of the north peppers are medium green when young and turn red when ripe. They are popular for both fresh eating and cooking.
Redskin
A dwarf, sweet bell pepper that's perfect for growing in pots and in the greenhouse. Considering how compact they are to grow, they are exceptionally high yielding for a large crop of sweet peppers, suited to both salads, dipping into hummus, or for cooking.
By growing a variety of bell pepper plants from seed, you can enjoy a range of flavours and colours in your meals. Whether you prefer sweet and mild peppers or spicy and hot ones, there is a bell pepper variety that will suit your taste and needs.
Step-by-Step Guide to Optimal Bell Pepper Growing
Here is a step-by-step guide to help you get started growing your own peppers:
Start seeds indoors about 6-8 weeks before the last frost date in your area. Bell pepper seeds have a relatively long germination period, so it is important to start them early. Fill a seed tray or pots with seed compost or a soilless mix and water well. Sow seeds about 1/4 inch deep and cover them with a layer of compost or vermiculite.
Place the tray or pots in a warm, sunny location, or use a heat mat to keep the soil temperature at around 21-24°C. Keep the soil moist, but not waterlogged, and consider using a plastic cover or propagator to help retain moisture and heat.
Once the seeds have germinated and the seedlings have emerged, transfer them to a greenhouse or a sunny windowsill. Keep the seedlings well-watered and fertilize every two weeks with a balanced liquid fertiliser.
When the seedlings are about 6-8 inches tall and the threat of frost has passed, transplant them into pots or the ground in your greenhouse. Choose a location that gets at least 6-8 hours of sunlight per day and has well-draining soil.
Water the plants regularly, keeping the soil evenly moist but not waterlogged. Mulch around the base of the plants to help retain moisture and suppress weeds.
As the peppers begin to grow, support them with stakes or cages to keep them upright. Prune off any suckers that grow from the base of the plant to direct the plant's energy into producing peppers.
To encourage fruit production, pinch off the growing tips of the plants once they reach the desired size. This will encourage lateral growth and more flowers and fruit.
Harvest the peppers when they are ripe and enjoy them fresh, or preserve them by freezing, drying, or pickling.
By following these steps, you should be able to successfully grow a healthy crop of bell pepper plants in your greenhouse. With a little patience and care, you will be rewarded with a bounty of sweet and spicy peppers that are sure to add flavour and nutrition to your meals. |
GROWING PEPPERS IN A GREENHOUSE
Growing Peppers in a Greenhouse
As we move into cooler weather, peppers are a great crop for inside your greenhouse. They have endless varieties and culinary applications, from Thai curry dishes to salsas and so much in between! Here's a few pointers:
1. Choose the Right Variety for your cooking needs: The first step to growing peppers in a greenhouse is to select the correct variety. There are many types of peppers available, including bell, sweet, and hot peppers. Research which peppers best suit your greenhouse environment and the desired flavor profile. Note the approximate time to maturity and what you'll use then for one they start cranking (use fresh, freeze, can, sell, etc).
2. Create the Ideal Growing Environment: Peppers thrive in warm temperatures and require ample sunlight to grow. A greenhouse provides the perfect environment for peppers, allowing you to regulate temperature, light, and humidity. Aim to keep temperatures around 25°C for optimal growth. It is also important to provide at least six hours of direct sunlight each day.
3. Choose the Right Soil Mix: Using the right soil mix is critical to growing peppers in a greenhouse. Peppers grow best in well-draining soil with a pH of 6.0 to 6.8. A mixture of peat moss, vermiculite, perlite, and compost may work well. Moreover, it is important to water thoroughly and regularly, and prevent the soil from drying out.
4. Fertilize Regularly: Along with water, regular fertilization also plays a significant role in the growth of pepper plants. Applying a balanced fertilizer at regular intervals every two weeks can provide sufficient nutrients for the pepper plants. A nutrient-rich herb compost can also be added to the top of the soil, which can slowly release the nutrients over time.
5. Prune and Stake the Plants: As pepper plants grow, they can become top-heavy and require support. Staking the plants prevents them from toppling over under their weight. It is best to use plant ties or soft twine to tie the plant’s stem to the stake so as not to damage the plant. Moreover, pruning the plants from their dead and damaged parts also encourages the growth of the new shoots or fruit.
6. Use them in your favorite dishes! Whether you're growing peppers for a specific dish, or because you want a new pepper culinary adventure, there are countless recipes on the internet you can find for the peppers you grow.
In conclusion, growing pepper plants can be easy and rewarding in a greenhouse. Choosing the right variety, creating an ideal growing environment, selecting the right soil mixture, fertilizing at regular intervals, and staking the plants will help you have a successful pepper harvest. Follow these simple steps, and you will have a bountiful crop of peppers in no time! |
Producing high quality ripe bell peppers is a challenge for many growers, as they are slower-growing and later
to mature than many other fruiting crops. As such, they are an increasingly popular crop for greenhouse
production: protected culture allows for an extended growing season, higher yields, and improved fruit quality
compared to field-grown crops. We aim to provide adequate growing instructions for those looking to grow
greenhouse-adapted pepper varieties in both low and high-tech greenhouse or high tunnel systems.
PROPAGATION:
Sow seeds 0.25–0.5 inches apart into 20-row flats in the
desired medium 6–8 weeks prior to transplanting.
Maintain a constant, 27–32°C soil
temperature to achieve an ideal germination
percentage and uniformity—heat mats are beneficial
for maintaining a consistent temperature. When the
first true leaves start to show, transplant the
seedlings into cell-type containers or blocks.
Containers 2 inches or larger will produce larger,
stronger root systems.
FERTILITY:
Peppers perform best in well-drained fertile soil with
high levels of calcium and phosphorus and a pH of
6.5–6.8. If you are growing a long-term crop that will
be in the ground for 4 months or more, it is not
possible to provide all the necessary nutrients from
pre-planting fertility; side dressing or fertigating with
extra nutrients will be necessary mid-way through the
growing season. Use plant tissue testing to monitor
the health of the plants and add extra nutrients when
necessary.
TRANSPLANTING/SPACING:
When transplanting into the greenhouse, try to
maintain temperatures of 23°C during the
day and 21°C during the night for the first
week to promote rapid vegetative growth and root
establishment.
For 2-stemmed plants, use a plant density of 3–3.5
plants (6–7 stems) per square yard (9 square feet).
For 4-stemmed plants of a medium-to-large-fruited
variety, maintain the same 6–7 stems per square
yard spacing, but with half as many plants. For 3–4-
stemmed plants of a small-fruited variety, plant at the
same density as if for a 2-stemmed plant (3–3.5
plants per yard); while this results in a very dense
row of vegetation, the plants can tolerate it and it
helps to offset the reduction in yield inherent to
growing these types compared to larger-fruited
varieties.
One common row-spacing method to achieve this
density is to grow two rows of plants per bed, trellised
to 2 parallel overhead wires 2 feet apart with
walkways 3 feet wide. Each stem is anchored 6
inches or so from the next one. Some growers prefer
to use 2 wires per row (4 total in a bed with two
rows): 1 wire positioned directly overhead the row of
plants and a second wire positioned 8 inches in from
the first set; this allows for alternating every other
stem along the row, and therefore spacing the
pepper stems out to 1 foot from each other on each
wire.
CLIMATE:
Peppers are naturally slow-growing and need warm
temperatures for fast growth. A very specific, ideal
growing regiment is described below, primarily for the
benefit of those growers with more sophisticated
greenhouse setups. Please note that if your
conditions vary modestly the plants will still produce a
crop, but the yield and quality might be slightly
compromised. While low-tech greenhouses with less
extensive climate control conditions cannot be
optimized to the same extent as high-tech
greenhouses, they still provide many benefits to the
grower beyond simple field production. Our
greenhouse pepper assortment has been trialed
extensively in low-tech conditions, and selected for
Bell Pepper
Greenhouse Production
Copyright © 2024 Johnny’s Selected Seeds. All rights reserved.
2
SEED BREEDERS, GROWERS, AND MERCHANTS SINCE 1973
their strong performance and adaptability, among
other qualities.
7–10 days after transplanting into the greenhouse,
lower night temperatures to 18–20°C and
keep a daytime temperature of 21–24°C. A
wider range between daytime and nighttime
temperatures generally promotes more generative,
fruiting growth whereas a flatter temperature profile,
with day and nighttime temperatures more even to
each other, encourages more vegetative, leafy
growth. Do not allow the greenhouse to fall below
16°C, or else all plant growth will stall. Peppers
have difficulty setting fruit at nighttime temperatures
above 20°C, so on warm summer nights it is
important to get the temperature below that level.
Temperatures above 32°C can sterilize pollen,
also leading to poor fruit set, so during the heat of the
summer it is especially important to be able to
effectively vent your greenhouse.
TRELLISING:
There are two common styles of trellising peppers in
a high tunnel or greenhouse: using stakes along with
a basket-weave system or growing pruned plants
with a restricted number of leaders vertically up to an
overhead wire. There are pros and cons to both
methods; briefly summarized, the basket-weave
system provides much needed support to the plants
for a minimum of labor input, but at the cost of
restricted airflow, risk to fruit quality, and a more
challenging harvest, whereas the branch-pruning
system, while much more labor-intensive, better
utilizes the vertical space of the greenhouse,
improves overall plant health and fruit quality, and
increases the overall longevity of the crop.
This document focuses on the methods and
techniques required for the branch pruning and
vertical trellising method. More information and an
instructional video about this method can be found on
our website at https://www.johnnyseeds.com/pepperlibrary. If you prefer to use basket-weave trellising,
please refer to or request our technical sheet,
Basket-Weave Trellising.
BRANCH PRUNING:
Each pepper plant is pruned to 2 or 4 stems, and
each stem is then trellised up a hanging string to
make the best use of vertical space. Growing
peppers on a 2-stemmed plant will result in larger
peppers than those grown on a 4-stemmed plant.
Two-stemmed plants will be more resilient under
hotter-than-ideal conditions. We recommend pruning
larger-fruited varieties to two stems and smaller
fruited varieties to four stems (the initial two stems
plus both subsequent branches). Here are the steps
for branch pruning:
1. Once the plants are big enough to start to
need support, tie strong twine to the
overhead wire at the desired spacing: you
will need as many separate lengths of
twine as the number of leaders you intend
to prune to. Synthetic twine is preferable,
as natural twine can degrade and break
under greenhouse conditions. (Image 1)
2. Anchor the other end of the twine just
below the lowest branch of the leader it
will be supporting with a loose knot or with
trellis clips. (Image 1) If the knot is too
tight it can damage or kill the plant. Twist
the stem of the plant around the twine or
clip with trellis clips every 2 weeks or as
needed to keep it supported and growing
up the twine. Clips should be positioned
directly below the branches to provide
better support and resistance against the
plant sliding down. Repeat this process for
each leader the plant has.
Copyright © 2024 Johnny’s Selected Seeds. All rights reserved.
3
SEED BREEDERS, GROWERS, AND MERCHANTS SINCE 1973
Image 1. Trellis and trellis clips
3. Remove the first (or “king”) flower that is
set in the first split (node) before the
pepper fully develops. This will give the
plant time to develop enough vegetatively
to support a fruit load. (Image 2)
Every node after the initial split will result
in 1 leaf, 1 flower, and 2 branches. Field
pepper varieties may sometimes form
three or more branches per node, but
greenhouse peppers are bred to more
consistently form 2 even branches. It is
typical to remove the flowers at the
second and third nodes, but if all
conditions are optimized, some growers
allow fruit to set after removing just the
first one.
Image 2: First split
4. At each node after the initial split, choose
the strongest of the 2 branches to
continue forming the stem. Terminate the
weaker branch, leaving the “flag leaf.”
This flag leaf will protect the pepper
directly below it from sunscald. (Images 3
& 4)
Image 3: The branch noted in green is kept
and the branch noted in red is removed.
The cut (marked with an x) is placed above
the flag leaf, which is marked in yellow.
Copyright © 2024 Johnny’s Selected Seeds. All rights reserved.
4
SEED BREEDERS, GROWERS, AND MERCHANTS SINCE 1973
Image 4: The terminated branch (marked in
red) retains the flag leaf.
5. Do not prune within 8 inches of the top of
the plant, taking care not to cause
damage to the growing point.
Prune every 2 weeks, or after about 6 inches of
growth since the last pruning. Bell pepper plants will
typically set 4–5 fruits before aborting the next few
flowers; it is normal for the plant to set fruit in
“flushes.” Remove fruits if they are deformed or
unmarketable to allow the plant to put the energy into
setting more fruit farther up the plant.
SUCKERING
Small side-shoots (usually called “suckers”) will
sprout at each leaf node. Suckers can be pinched off
the main stem to promote airflow and general plant
health. (Image 5)
HARVEST:
Harvest fully ripe fruit for immediate sales. If not
being sold right away, harvest peppers when they are
80% or more final ripe color. They will reach full color
in storage. Using pruners or a knife, cut the fruit off
flush with the main stem of the plant. Make sure not
to leave a stub on the plant, as this can be an entry
point for pathogens.
Image 5: Suckers
DISEASES AND PESTS:
Practice crop rotation or use new media to reduce
incidence of soil-borne disease. Minimizing the
amount of time with temperatures below 18°C
will reduce the amount of botrytis.
Pests that may be a problem include aphids, thrips,
pepper maggot, and multiple types of boring
caterpillar. If insect pests are a problem, release
beneficial insects to control pests. Preventative
applications of DiPel® can be an effective control for
caterpillars.
STORAGE:
Peppers should be stored at 7–8°C and 90–
95% relative humidity. Do not store them with
ethylene-producing vegetables like tomatoes, as
ethylene will promote ripening to the point of being
overripe.
REV 2/9/2 |
How to grow and care for bell peppers – for a bumper crop
Discover how to grow and care for bell peppers to enjoy a colorful homegrown harvest to add to a wide range of dishes and salads
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how to grow and care for bell peppers in a garden
(Image credit: Getty Images)
Rachel Crow
BY RACHEL CROW
PUBLISHED 27 MARCH 2022
Once you know how to grow and care for bell peppers you can enjoy the vibrant and colorful crop as part of your homegrown harvest.
Also know as sweet peppers, or capiscum, bell peppers come in a variety of colors, shapes and sizes, and edible both raw or cooked, are highly versatile for use in a wide ranges of cooking and dishes.
Bell peppers are certainly one to add to your vegetable garden ideas as an economical crop to grow – the cost of one pepper at the grocery store will far exceed the cost of growing from seed your own pepper plants, which will produce numerous fruits.
How To Grow And Care For Bell Peppers – For Beginners
When it comes to how to growing bell peppers, there are a various options and the best method to use will depend on the zone in which you live.
Sweet peppers are tender plants that thrive in warm conditions. If you live in a colder area you will probably enjoy greater success growing bell peppers in a greenhouse or under cover, whereas those living in warmer or milder regions can still enjoy a healthy crop from planting them outside.
You can also encourage bigger and healthier crops by pepper companion planting with beneficial plants, as an organic way to protect the peppers from pests and improve pollination of fruits.
companion_planting_peppers_nick-fewings-unsplash
(Image credit: Unsplash)
Where To Grow Bell Peppers
First assess your local growing conditions before deciding how to grow bell peppers.
Sweet peppers need warmth and a sunny position, so tend to produce higher yields when grown under cover in cooler regions. You can add them to your list of crops to grow when planning a greenhouse.
They can also be grown outside in warmer areas, but in all cases they can benefit from being sown indoors and started off in a warm environment, before being planted out, where relevant.
Another option is growing bell peppers as a vegetable garden container idea. The benefits of this are you can move the pots around to make sure the pepper plants benefit from the sunniest and most sheltered conditions.
'Bell peppers can be grown in a variety of situations and do well in greenhouses, outside gardens and even containers. Some gardeners choose to start peppers from seed, while others prefer to buy plants already coming up and ready to transplant into the soil. With good soil, fertilizer, sun, and water, one should have good results,' explains Gina Abernathy, owner of Abernathy Farm Supply in Alabama and founder of Home at Cedar Springs Farm.
Growing Bell Peppers From Seed Indoors
red bell pepper growing on plant
(Image credit: Getty Images)
Start off growing bell peppers by sowing the seeds indoors to give them a head start and help them to germinate – this is essential if you live in a cooler region.
Seeds should be sown indoors about 8 to 4 weeks before the last frost, as they take a while to grow.
Sam Corfield, author of Sow, Grow Gather: The beginner's Guide to Growing an Edible Garden suggests the following method for planting bell pepper seeds indoors:
Fill an 3in (8cm) pot with compost almost to the to top
Use a pencil or small dibber to poke four evenly spaced holes into the surface of your pot, 1/2 in (1cm) deep
Pop one seed in each hole, cover with a little more compost and give them a gentle water
Leave your plants on a warm windowsill with a plastic bag over the top, or in a propagator – they like to be around 18-21°C
Don’t let them dry out
Take the pot out of the propagator or remove the plastic bag as soon as the seedlings start to appear, and keep in a warm, sunny spot, at about 16-18°C.
Once the seedlings have grown to about 5in (12cm) tall and have at least two true leaves, transplant them into their own 3in (8cm) pot filled with potting compost.
Continue to pot them on as the roots start to grow out of the drainage holes into a final pot of about 12in (30cm).
'The more heat they get the better, so keep them indoors by a sunny window, in a south-facing spot outside, or in a greenhouse,' advises Sam Corfield.
How To Grow Bell Peppers From Young Plants
bell pepper seedling growing in pot
(Image credit: Getty Images)
If you don't have time or are too late for growing bell peppers from seed, then you can find young plants at garden centers in late spring and early summer.
Plant them outdoors in a sunny, sheltered spot once the danger of frost has passed, or grow in a greenhouse, polytunnel or by a sunny windowsill in a conservatory or garden room.
Peppers are very sensitive to cool temperatures, so harden off young plants prior to planting them outdoors to allow them to acclimatize to the change in conditions. |
Cucumbers are best sown indoors, as they can be started off earlier to get an earlier crop. Germination is also more reliable and young plants are easier to look after until they’re more resilient. They should be moved to their final growing position after about a month.
Seeds of outdoor varieties can also be sown outside in mild locations, once the soil has warmed up in early summer.
Sowing indoors
Sowing times depend on where you’re ultimately going to grow the plants.
Sow in:
Mid-February to mid-March – if you’ll be growing them in a heated greenhouse
April – if they’ll be growing in an unheated greenhouse, polytunnel or large cold frame
Late April – for growing outdoors
Fill 10cm (4in) pots with seed compost, water well, then sow one seed in the centre of each, 1–2cm (1/2–3/4in) deep. Position the seeds on their side to prevent rotting.
Place the pots in a
A heated propagator is a portable heated structure with a vented lid and adjustable, constant, thermostatic temperature control. It provides a warm, humid environment to help seeds germinate and cuttings to root quickly.
heated propagator at 21°C (70°F) or on a warm sunny indoor windowsill.
Remove from the
A propagator is a portable, lightweight structure usually plastic, with a vented or unvented lid to provide a humid, slightly warmer atmosphere. It is useful to help seeds germinate and root cuttings. It may have adjustable, thermostatic temperature control.
propagator once
A seedling is a young plant grown from seed.
seedlings appear, which may take one to two weeks. Continue to keep the young plants warm, in bright light, and water regularly.
Sowing indoors has several advantages:
Reliably warm conditions, which should lead to better germination.
Keeps the seedlings out of reach of slugs and snails.
Protects seedlings from poor weather.
Indoor-sown cucumber plants or newly bought plants should be settled into their final growing site in spring or early summer, depending on where that will be:
Greenhouse cucumbers – transplant into their final growing container or a greenhouse border in late March (in a heated greenhouse) or late May (in an unheated greenhouse, polytunnel or cold frame), as long as the temperature can be kept above 12–15°C (53–59°F).
Planting them is very straightforward – water well beforehand and try not to disturb the rootball, so they settle in quickly without a check in growth:
To plant in a container – choose a pot that is at least 30cm (1ft) wide and deep, and fill it with good quality potting compost. Position one plant in the centre, firming it in gently then watering generously. You can also plant two cucumbers in a growing bag.
To plant in the ground – either outdoors or in a greenhouse border or polytunnel, prepare the soil (see Preparing the ground, above) then plant 30cm apart, firming in gently and watering well.
Cucumbers are climbing or scrambling plants that can either be grown up supports or allowed to trail on the ground. Growing them vertically means they take up very little ground space, which is useful in small gardens as well as small greenhouses.
Put the supports in place at planting time – bamboo canes, wires, strings, netting, trellis or anything similar that their tendrils can
Twine is a soft, fine loosely woven string treated with preservatives for outdoor use. Used for tying in climbers and other plants to supports.
twine around. They can’t cling to flat surfaces. The stems need tying in initially, and may need help later if they lose their way or come loose, especially outdoors and when laden with fruit.
With greenhouse cucumbers – insert a tall, sturdy bamboo
A cane is a slender, straight, length of woody plant material, usually bamboo. Canes are primarily used as plant supports. The fruiting stems of blackberries, raspberries and hybrid berries (such as loganberries and tayberries) are also known as canes, so these crops are often referred to as cane fruit.
cane up to the greenhouse roof, or attach a vertical wire or string from the roof, secured at ground level. Horizontal supports may also be required for side-shoots.
Cucumbers, whether grown outdoors or in a greenhouse, polytunnel or cold frame, need warmth and regular watering to crop well. When grown in containers, they need additional watering and feeding too.
Watering
Water little and often, to keep the potting
Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.
compost or soil evenly moist. Take care to water at the base of the plants and avoid wetting the leaves, which can encourage fungal diseases.
Feeding
Feed cucumber plants in containers every 10–14 days with a general liquid fertiliser.
Once they start flowering, change to a weekly tomato feed, to encourage flowering and fruiting.
Pinching out shoots
It’s a good ideal to restrict the vigorous growth of cucumbers, so they concentrate on making fruit rather than growing too large:
With greenhouse cucumbers,
Removal of a plant’s growing tip (usually with finger and thumb) to encourage it to produce side-shoots, forming a bushier, well-shaped plant that will bear more flowers and/or fruits.
pinch out the growing point when it reaches the greenhouse roof. Also pinch out the tips of side-shoots two leaves beyond a female flower (which has a tiny fruit behind it). Pinch out the tips of flowerless side-shoots once they reach 60cm (2ft) long.
Removing male flowers
Most greenhouse varieties are all-female (check seed packets for details), producing almost exclusively female flowers (with a tiny fruit behind them). These must not be pollinated, otherwise the resulting fruits will be bitter. Occasionally male flowers (without a tiny fruit behind them) may appear, in which case remove them.
Temperature and humidity
In greenhouses, raise the
The amount of water vapour in the atmosphere. Different plants require different levels of humidity. Houseplants that need high humidity are best grown in a steamy bathroom, misted regularly or the pot placed in a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor, overhead watering or misting. However, high humidity can cause fungal problems, in which case open vents to improve ventilation.
humidity in hot weather by pouring a watering can over the concrete floor or central path, so the water evaporates. High humidity also deters red spider mites and powdery mildew.
Greenhouses can get extremely hot in summer, so put up shading to keep temperatures lower, ideally 18–25°C.
Cucumbers ripen from mid-summer to mid-autumn in a greenhouse, with a shorter season outdoors depending on the weather.
Fruit size varies according to the variety. In general, smaller-fruited varieties are best at about 10cm (4in) long and full-sized varieties at about 15–20cm (6–8in). The fruits should be uniformly green and firm, usually with a slightly rounded tip.
Fruits can grow rapidly, so check them regularly to get them at their best. If they turn yellowish, bulbous or soft, they are likely to be over ripe.
Cut the stem cleanly with a sharp knife or secateurs, rather than pulling. Regular harvesting encourages further fruiting.
Cucumbers are tender plants and need warm temperatures to germinate and grow strongly, and ideally 18–25°C to crop well. They also need regular watering, especially when flowering and fruiting.
Although usually healthy and vigorous, they can be weakened by
A white powdery fungal growth on the surface of leaves, buds, petals and shoots of roses and many other plants. The foliage may become discoloured, heavily infected young leaves may be curled and distorted, and the plant’s vigour may be reduced.
powdery mildew and red spider mites, especially in greenhouses and if
The amount of water vapour in the atmosphere. Different plants require different levels of humidity. Houseplants that need high humidity are best grown in a steamy bathroom, misted regularly or the pot placed in a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor, overhead watering or misting. However, high humidity can cause fungal problems, in which case open vents to improve ventilation.
humidity is low. Mildew-resistant varieties are available. Protect young plants from slugs and snails. Mosaic virus is a more serious problem, and affected plants should be destroyed. |
Learn the basics of greenhouse cucumber production, including seeding production; training, pruning, and spacing; the greenhouse environment; fertilization and irrigation; and harvesting and fruit quality.
Cucumbers are a popular crop for greenhouse vegetable production. English and Beit Alpha are the two primary cucumber types grown in greenhouses. Both types are parthenocarpic, meaning they produce fruit without flower fertilization and do not require pollination. Due to the absence of a fertilized ovule in the fruit, these cucumbers have no seeds and are marketed as “seedless.”
Cucumbers are typically tolerant of extreme summer temperatures and are considered a fast crop with the first harvest ready within as little as 7 weeks from seeding. This fast turnover time allows for great flexibility in crop cycles. Cucumbers perform somewhat better than tomatoes in extreme summer temperatures; however, yield can suffer in the winter with low light levels and conservative heating strategies. An ideal crop timing has not yet been established in Alabama; however, research trials show that two crop cycles per year are an efficient model. A spring crop can be seeded in December for January transplanting and harvested from February to July. The harvest interval of a spring crop can extend past 12 weeks, depending on greenhouse temperatures. However, In the southeastern United States, temperatures typically exceed ideal growth conditions by July, and the spring planted crop is removed. For a fall crop, seeds are started in July, transplanted in August, and harvested from September to December.
Seedling Production
Starting cucumbers in flats from seed before transplanting them into the production system saves valuable time and production space in the greenhouse. Seeds can be started in a 50-cell (11′′x22′′) or larger nursery flat using a peat-based potting mix. Irrigate seedlings with plain water until true leaves have emerged, then switch to a half-strength fertilizer solution (50-100 ppm N).
Growing Systems
Vine crops such as cucumbers, tomatoes, and peppers are often grown in substrate-based systems. This method differs from true hydroponics (nutrient film technique and deep water culture) in that a soilless substrate is used to support the root system and provide a higher degree of aeration.
Three main types of substrates are used in greenhouse production. Perlite and pine bark are the most common substrates used in the southeast. Perlite is a volcanic rock that has been expanded by heat treatment. It is a lightweight, highly porous inert substance that does not contain or hold nutrients. Pine bark is an organic material that can hold some nutrients. Pine bark is typically milled to 1⁄2 inch and should be aged before use. Rockwool is another substrate used to cultivate crops; it is primarily used in high-wire systems. Rockwool comes in large cubes or slabs and often rests on plastic troughs to drain nutrients. Rockwool seedling blocks are also used for transplant production. These blocks are placed on top of Rockwool slabs or other soilless media. Rockwool is inert like perlite and has a high water- holding capacity.
Several substrate production systems can accommodate cucumber production using the aforementioned substrates (figure 1):
Dutch bucket: a plastic bucket fitted with a drainage hole in the bottom for nutrient solution to flow out and be reused if desired. Perlite and pine bark can be used in dutch buckets.
Bag culture: a flexible plastic bag is filled with the desired substrate, and drainage holes are poked on the bag’s underside to allow for water and airflow through the substrate. The bags can be positioned horizontally or vertically under the trellis system. Holes are cut in the top of the bags for transplants. Perlite and pine bark can be used with bags; however, perlite seems the most popular.
Nursery pots: typically 3- or 5-gallon plastic pots used in the ornamental nursery industry. Both perlite and pine bark substrate can be used with nursery pots.
Slab culture: a slab made of Rockwool is used to anchor plant roots and hold water.
Training, Pruning, and Spacing
Cucumbers are trained to grow vertically on strings suspended from a wire cable. The trellis system should run parallel with the greenhouse. Advanced greenhouse systems commonly used in northern climates use a high-wire system where crops are grown on strings suspended from trellises with heights over 12 feet (figure 2). This system favors cooler climates in terms of efficiency and has not been thoroughly validated in Alabama. Most greenhouse vegetable operations in the southern states use a similar trellis system, but they are considerably shorter in height (6 to 8 feet).
Growing plants upright takes advantage of the vertical space in the greenhouse and allows for high-density planting. Rows are typically spaced on 5-foot centers. A 30-foot wide greenhouse will support 5 rows.
Plants can be trained and pruned several ways resulting in various plant densities (plants per area). The optimum density isn’t always the highest. In some cases, too many plants can result in lower yields. The optimum density maximizes yields with available light. Plant density might be reduced by 25 percent or more in the winter months to maximize light available to leaves.
The two training methods are the vertical cordon and the v-cordon system. In both systems, flowers are not allowed to form until the sixth or seventh true leaf, allowing a more favorable leaf:fruit ratio. Fruit abortion and malformed fruit are problems when over-fruiting occurs.
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Cucumbers grow quickly so you don’t have to wait for a long time to harvest them. You can raise them regardless of how much area you possess especially when you use a trellis. They can also be successfully planted in charming pots, growing bags or right on the ground. Stop worrying about how to grow cucumbers in a greenhouse. We have prepared that for you.
Two main varieties of cucumber
Greenhouse cucumber variety creates long, delicious fruits, just like the ones you buy in the market. It doesn’t require pollinating. As a matter of fact, you have to eliminate all-male flowers to stop pollination from occurring or it will turn out to be bitter.
Quick overview of growing cucumbers in a greenhouse
Type: Warm-season crop
Time from seed to harvest: 50-70 days
Germination temp: 18.3°C
Time until first emergence: 3-14 days
Best temp to grow: 23.8-29.4°C
Height: 3-12 ft
Spread: 1-4 ft
Grow from seed: 1/2-1 in deep, 12-15 in apart
Companions: Radish, dill, tomatoes, marigolds, lettuce, corn, peas, beans
Keep away from: Brussels sprouts, kale, cauliflower, kohlrabi, melons, potatoes
Let’s talk more about growing cucumbers
Cucumbers are generally monoecious. There are male and female flowers on each plant. Learn a lot about how to grow cucumbers in a greenhouse and distinguishing male from female flowers:
You can recognize male flowers easily because they have a plain stem. Female flowers look like they have a little cucumber or a tiny, underdeveloped sprout of fruit between the base of the flower and stem.
Cucumber is a widely cultivated vegetable in the gourd family. It is a crawling vine that produces cucumiform fruits. Cucumbers are rich in potassium, flavonoids and Vitamin K. Cucumbers are technically fruits and are easy to grow in a greenhouse. Here is how:
Steps on how to grow cucumbers in a greenhouse
Sow the cucumber seeds in the last three weeks before the frost date so that you can transplant them one week after the frost subsides. This is important because cucumbers are very vulnerable to frost damage. Greenhouse Heaters will help you achieve the required warmth your cucumbers need in those freezing periods. This way you don’t have to think about frost dates and are able to grow them throughout the year.
Growing cucumbers in pots are also great. Sow one seed per three-inch pot. This gives them sufficient place for initial plant growth.
Make sure you sow them in peat pots or a little flowerpot made of peat in which a plant can be raised and transplanted without having to be extracted because the root systems should not be disturbed.
Three weeks after starting the seeds, prepare a patch inside your greenhouse where you will transplant the seedlings.
Alternatively, you can transplant the seedlings into hanging pots or in growing bags.
The appropriate spacing is 12 to 15 inches apart if you are transplanting them on the ground inside the greenhouse or on raised beds.
Take advantage of your vertical space
Growing cucumbers on trellis promote more side shoots and will create bigger cucumbers. Back up your cucumbers to climb and generate excellent yields. Guide the main shoots to rise using a trellis. When they finally touch the edge of the trellis, take out the developing part at the top. Remove the end of each side shoot once it begins to expand, leaving two leaves per fruit.
5 great greenhouse accessories for your cucumbers
Increase your harvest by starting right in the first place. Starting your cucumber plants in the RSI Hydroponic Floating Seeding Tray does not damage the delicate roots of your precious crops.
With the Juliana Flexible Plant Spirals, you can keep your cucumbers inside your greenhouse while giving them the vertical length to grow. Create beautifully arranged cucumber plants. It is adjustable and will fit any height or length up to six feet.
Switch into self-watering planters to prevent your plants from withering. Do more gardening chores and spend little time on watering. Calypso Planter with Trellis and Reservoir gives a classic look to your climbing cucumber plants and can also save you some space.
Consider investing in a raised bed with trellis. The Eden Garden Bed with Trellis is the perfect garden bed for your cucumbers and other plants you want to transplant into the garden.
Personalize your garden with the Wooden Trellis Screen & Planter System. You can assemble the trellis in any way you want. Place this anywhere depending on your cucumber’s needs.
Training your cucumbers in two ways
Using the triple stem training method means that all the suckers or root sprouts are taken off the establishing vine up to the tip of your trellis. Pinch the final buds of the main stem at the top of the trellis and leave three suckers to grow.
The next approach is lateral growth training which means all suckers are taken off for the initial four to five fruit sets. The next eight to ten suckers are left to grow one leaf and one flower. Then, squeeze the tip of the sucker. All the leftover suckers over the eight to ten must produce two leaves and flowers. Pinch the surviving growth. Trellis bar should be roughly six feet over the ground.
Pests control
Some common pests that attack cucumbers are whiteflies and cucumber beetles. The plant is vulnerable to diseases such as bacterial wilt, mosaic virus attack, and anthracnose. Signs of inadequate nourishment are yellow leaves, underdeveloped or failed to fruit.
Greenhouse whiteflies are possible pests in the spring and summer months. Adults are obvious but detecting young larvae requires the help of the lens. The effectiveness of yellow sticky traps or biological control can also give huge help.
Proper watering
Cucumbers require moderate watering. After the plants emerge, the appropriate amount of water per plant is about a gallon every week. Or follow the “little and often” rule. Manage your watering plan and volume with these Greenhouse Watering Systems.
Good soil conditions
Cucumbers thrive in neutral to light alkaline soils that range in pH from 6.0 to 7.0. However, the plants show tolerance even in soils that have pH levels nearing 7.6. A light liquid fertilizer twice a month or so will be beneficial once the fruits start to grow.
Prep for a perfect light and warmth
For effective germination, the bottom heat of the sprouting medium should be about 70°F. Set a soil thermometer in the spot where cucumbers will be located. If the soil temperature falls under 60°F, growth will cease and overall health will worsen. It cannot endure the freezing temperature.
Cucumbers require plenty of sunlight so ensure you set your greenhouse kit in such a way that it allows at least six hours of direct sunlight. Maintain a warm and humid interior by regular misting. You may have to screen your plants to guard them against scorching hot days. Or some shade is better. Keep your greenhouse cooler with these Shade Cloths.
The exciting part of all! Harvesting!
You can harvest 20 to 50 cucumbers per plant. You can start reaping your cucumbers approximately 12 weeks from planting when they reach between six and eight inches. But again it is best to pick them while they are fresh preferably before they reveal indications of bearing seeds. Older fruits can grow bitter. Frequent harvesting will promote an endless yield. To harvest the ready fruits, cut them at the base using a sharp knife. An early morning harvest is advised while it is cold. The seeds are usable for three years or longer if properly stocked. |
Benefits of growing cucumbers in a greenhouse
With our variable summers, many gardeners choose to grow their cucumbers and tomatoes (Solanum lycopersicum) in a greenhouse. Providing protection from the elements, especially at night, a greenhouse can either be warmed by just the sun or with a supplementary heat source as well. Even an unheated greenhouse can provide precious warmth early on in the season, meaning that cucumber plants can get a 2 to 3 weeks head-start over those planted outside. With additional heating or when using a hotbed, a heated greenhouse can mean cucumbers can be planted even earlier in April, giving months of growing time ahead. However, greenhouses do not just provide the opportunity for earlier plantings but can also extend the season into October as the temperatures begin to dip outside.
Grown vertically in a greenhouse, cucumbers require strings or canes to be tied into as they grow. Not only is growing cucumbers vertically a space-saving method, but it can increase air circulation, which can help prevent disease and make plant care and harvesting the fruits easier. For more information on how to support cucumbers, check out our article on cucumber trellis.
Even with good ventilation, at the height of the summer, greenhouses can become too hot and reach temperatures over 45 °C. To avoid heat stress, sunburn and scorching of the foliage, damping down and shading the cucumber plants with white fabric and even the whole greenhouse, may become necessary.
When grown in a greenhouse or polytunnel, cucumbers are protected from wet weather, which when prolonged, can lead to fungal diseases occurring. However, other cucumber diseases can still be a problem and preventative measures may need to be taken. Pests can also be an issue when growing undercover, especially aphids (Aphidoidea), which can transmit diseases, but can be dealt with by introducing predatory ladybirds (Coccinella septempunctata) and lacewing larvae (Chrysoperla carnea).
Benefits at a glance:
Longer growing season, due to earlier planting
Protection against wind, rain and hail
Space-saving method of growing vertically
Controllable lighting and temperature by shading and damping down
Pest control by introducing beneficial insects
Cucumbers do not have to be grown in a greenhouse, as you can successfully grow cucumbers in a raised bed in a sunny and sheltered location. Furthermore, if you are short of growing space you can even grow cucumbers in pots.
The best cucumber varieties for greenhouses
There are many cucumber varieties available to grow that can differ in habit, fruit size, colour and even shape. However, when growing cucumbers in a greenhouse or polytunnel it is worth growing cultivars bred for growing under cover, as they tend to be more prolific and have increased resistance to the most common greenhouse diseases. Here are some of the best cucumber varieties for growing in a greenhouse:
‘Burpless Tasty Green F1’: forming long ridge-type fruits up to 30cm in length, this cultivar produces delicious non-bitter fruits that can be harvested around 60 days after sowing.
‘Carmen F1’: long, slender and straight fruits up to 40cm in length. Good tolerance against mildew and cold weather. Awarded the RHS Award of Garden Merit.
‘Emilie F1’: producing heavy yields of green fruits harvested at 20cm long, this hybrid cultivar has been awarded the RHS Award of Garden Merit. Good disease resistance and superbly flavoured fruits.
‘Mini Munch F1’: heavy yields throughout the season of small fruits harvested when 8cm or longer. Superb flavour and crunchy. Awarded the RHS Award of Garden Merit.
‘Socrates F1’: prolific small fruits harvested when 15cm long. Bitter-free taste and an excellent flavour. Awarded the RHS Award of Garden Merit.
‘Telegraph Improved’: an improved version of the long-grown heirloom variety. Long and smooth-skinned green fruits up to 30 – 40cm, with a mild and crisp flavour.
How to plant cucumbers in a greenhouse
When grown in a heated greenhouse, cucumber seeds are sown 1 to 2cm deep in individual pots from late February to March. For an unheated greenhouse, it is best to wait until April to begin sowing or alternatively sow indoors. Requiring a temperature of 21 °C to germinate, cucumber seeds are often sown in a propagator to provide this warmth. Find out more on planting cucumbers in our expert article.
Once the young cucumber plants are large enough, they can be potted on or planted out into a trench in a heated greenhouse from late March, or in an unheated greenhouse in late May. Cucumbers prefer a rich and fertile soil and benefit from being fed during the growing season. On planting, a slow-release granular fertiliser can be added to the soil, which will help provide nutrients to encourage strong and healthy growth. Our Plantura Tomato Food contains the necessary nitrogen, potassium and phosphorus to feed the cucumber plants for up to 3 months.
When growing cucumbers in a greenhouse, it is advisable to provide good air circulation between the plants, which can help prevent disease. Planting at a minimum spacing of 45 to 50cm and if space allows, even more, is recommended. On planting, canes can be inserted into the soil or strings hung from the roof to train the vines upwards. Water thoroughly and keep the soil moist but not wet.
Good companion plants
Companion plants are those that can be grown together for mutual benefit and not compete against each other. Companion plants for cucumbers include those that are light feeders and not part of the same Cucurbitaceae family of plants.
Tomatoes are often grown in a greenhouse, as they prefer similar growing conditions to cucumbers. They can be grown together in a greenhouse, but to stop them competing for each other’s nutrients and space, it is advisable to plant them in separate areas away from each other.
Companion plants for cucumbers can include:
Borage (Borago officinalis)
Calendula (Calendula)
Lettuce (Lactuca sativa)
Fennel (Foeniculum vulgare)
Dill (Anethum graveolens)
Onion (Allium cepa)
Garlic (Allium sativum)
Polyculture or mixed culture gardening does not just work outside in the garden, it can be beneficial inside a greenhouse as well.
Cucumber plant care in the greenhouse
Whether grown outdoors or in a greenhouse, cucumbers need to be watered and fed regularly throughout the growing season. Along with providing enough moisture and nutrients, pruning cucumbers can also help encourage a good harvest and prevent disease.
Watering and fertilising cucumber
Cucumbers prefer a moist but well-drained soil, so regular watering is a must to prevent the soil from drying out. Where possible, harvested rainwater is recommended as well as adding a layer of mulch to help conserve moisture and prevent weeds.
Cucumber diseases that can affect cucumbers in a greenhouse
Good ventilation is key for growing in any greenhouse, as if unventilated, the humid warm air can quickly become stagnant and encourage fungal diseases. Here are some of the most common cucumber diseases that can affect plants when grown in a greenhouse:
Cucumber Mosaic Virus
Cucumber wilt caused by Fusarium and Verticillium fungi
Cucumber downy mildew (Pseudoperonospora cubensis)
Cucumber powdery mildew (Podosphaera xanthii and Erysiphe cichoracearum)
Grey mould (Botrytis cinerea)
Sclerotinia disease (Phomopsis sclerotioides)
If cared for correctly, cucumber plants can produce impressive yields for weeks on end. Learn more about how to harvest and store your cucumbers. |
VARIETIES SUITABLE FOR GROWING CUCUMBERS IN A GREENHOUSE
Here are some cucumber varieties ideally suited for greenhouse growing:
Miniature Cucumbers: Varieties like ‘Mini Munch’ or ‘Picklebush’ are perfect for greenhouses due to their compact growth habits. They produce small, crisp cucumbers that are ideal for pickling or snacking.
European or English Cucumbers: ‘European’ or ‘English’ cucumber varieties, such as ‘Diva’ or ‘Passandra,’ are known for their long, slender, and seedless fruits. They perform exceptionally well in greenhouses, producing high yields of delicious, mild-flavoured cucumbers.
Dwarf Bush Cucumbers: Varieties like ‘Bush Champion’ or ‘Fanfare’ are bred specifically for smaller spaces like greenhouses. They have a bushy growth habit, making them ideal for containers or limited garden space within the greenhouse.
Slicing Cucumbers: For those who prefer traditional slicing cucumbers, consider ‘Sweet Success’ or ‘Tasty Green.’ These varieties offer excellent flavour and are well-suited for greenhouse cultivation, providing a steady supply of crisp, juicy cucumbers.
Hybrid Varieties: Many hybrid cucumber varieties are designed to excel in controlled environments. They often exhibit disease resistance, high productivity, and exceptional flavour, making them great choices for greenhouse gardens.
TOP TIPS FOR SUCCESSFUL CUCUMBER GROWING
Greenhouse cucumbers will need to be raised in grow bags (two per bag), beneath the protection of glass. In order to get the best results from growing them in this environment, we recommend you follow these top tips:
Set up for sunlight. Cucumbers need plenty of it, so be sure to set up your greenhouse in a way that will allow for around six hours of sunlight a day.
Remove male flowers. Some types of cucumbers are monoecious, meaning that they produce both male and female flowers on the same plant. You’ll need to remove the male flowers in order to prevent the fruit from becoming bitter. It’s easy to tell them apart, as female flowers have a swelling underneath them.
Choose an effective training method. Cucumbers grown in a greenhouse will require training. We recommend securing stems to the cane and pinching out the tip once it reaches the roof. Be sure to also pinch out the shoots from side branches.
Water moderately. Once your plants emerge, you’ll want to give each one roughly a gallon a week. Little and often is always a good rule of thumb!
Keep pests at bay. Lots of critters are attracted to cucumbers, such as whiteflies and beetles. Try using sticky pest boards to trap them teamed with an insecticidal control agent.
Ensure you have good soil conditions. Neutral to slightly alkaline soils are best for cucumbers, moist but never soggy. Use a light liquid fertiliser around twice a month to keep it in the optimal condition.
Your plants should be ready after around 12 weeks. They tend to reach between six and eight inches in height, and you can harvest as many as 50 cucumbers per plant. We recommend picking them before they show signs of bearing seeds, as the older a plant is the more bitter it can taste. Simply cut your cucumbers off using a pair of secateurs or a sharp knife. |
Select the Right Variety of Cucumbers to Grow in a Greenhouse
Bella Cucumber
F1 Bella
When it comes to growing cucumbers in a greenhouse, you have several options when it comes to varieties. Here are some of the most popular varieties:
F1 Bella – An all-female hybrid cucumber with good resistance to powdery mildew and no bitterness. Produces vigorously and thrives in an unheated greenhouse.
Cucumber ‘Diva’ – A mini-cucumber that provides particularly high yields when grown in a greenhouse. No seeds and smooth skins containing crisp flesh.
Cucumber Passandra F1. Organic mini-cucumber that is resistant to powdery mildew and crops heavily. Expect crisp and sweet flesh.
Starting the Cucumbers from Seed vs Buying Young Plants
When it comes to growing cucumbers in a greenhouse, you have two options: starting the cucumbers from seed or buying young plants. Here are some of the pros and cons of each option:
Benefits of Starting Cucumbers from Seed
Cucumber Seedlings
Cucumber seedlings
Cost-effective: Starting cucumbers from seed is a cost-effective way to get started in greenhouse gardening. Seeds are relatively affordable, and they allow you to grow a large number of plants relatively cheaply.
Flexible: Another benefit of starting cucumbers from seed is that you have greater flexibility in terms of the type of cucumber you can grow. You can choose from a variety of heirloom and hybrid varieties that are not available as young plants.
Sustainable: Starting cucumbers from seed is also a more sustainable way to garden. You can save money on plastic pots and soil by using recycled materials to start your plants.
Benefits of buying young cucumber plants to grow in your greenhouse
Young cucumber plants
Young cucumber plants
Convenience: One of the biggest benefits of buying young cucumber plants is that they are available when you need them.
Less time-consuming than growing from seed: growing from seed is time-consuming. The seeds need to be started indoors, and the plants will only be ready for planting in your greenhouse when they are about 2 months old, whereas shop-bought plants are ready to plant immediately.
How to Grow Cucumbers From Seed
When it comes to starting cucumbers from seed, there are a few things you need to keep in mind. Here are some tips on how to get started:
Start Seeds Indoors. Most cucumber seeds need to be started indoors about 6-8 weeks before you plan to transplant them into your greenhouse. Either use a heated propagator or germinate in a polythene bag. Germination normally takes 5-7 days.
Pot the seedlings on when they’re about a month old into 12cm pots. Ensure plants are kept at a temperature above 15 ℃.
Prepare the Soil to Grow Cucumbers in Your Greenhouse
When preparing the soil to grow cucumbers in a greenhouse, it is important to consider the needs of the plants. Here are some tips on how to get started:
Choose a Good Location
When choosing a location for your greenhouse, make sure to pick a spot that gets plenty of sunlight. Cucumbers need at least 6 hours of direct sunlight per day to produce fruit.
Amend the Soil
Before planting your cucumbers, it is important to amend the soil with compost or other organic matter. This will help to provide the plants with the nutrients they need to grow strong and produce fruit.
Use a Large Container
If you’re growing cucumbers in a container, be sure to use one that is at least 18 inches deep. The container should also have plenty of drainage holes to prevent waterlogging or root rot.
Transplant the Cucumber Plants into the Greenhouse
When the cucumber plants are 2 months old, you can transplant them into your greenhouse. Be sure to space them out so they have enough room to grow.
Growing Tips for Your Greenhouse Cucumbers
Cucumber greenhouse trellis
Ensure cucumbers are well-supported
Once you’ve transplanted the young plants, here are a few tips to help them thrive:
Remove any male flowers to stop the fruit from becoming bitter (if the variety demands it). Male flowers do not have the swelling of the growing fruit underneath them.
Train the plants on a trellis or up strings. Cucumber plants in full fruit can be surprisingly heavy so ensure the support can withstand the weight.
Spray overhead in hot weather.
Pinch out the tops of plants when they reach the desired height – or train them to grow in another direction (but ensure they’re well supported). Also pinch out any side shoots.
Pick fruit regularly to encourage more fruiting and harvest before they become too large.
Regularly pile fresh compost around the base of the stem. Feed with a liquid feed every 10 days.
Remove any yellowing or damaged leaves.
Common Problems with Greenhouse Cucumbers
Cucumber plant affected by powdery mildew
Cucumber plant affected by powdery mildew
Powdery Mildew – Appears on plants as white, powdery patches. It’s often caused by underwatering – water plants frequently to prevent, or buy a resistant variety of cucumber.
Cucumber Mosaic Virus – Leaves marked by a yellow mosaic pattern. Remove and destroy affected plants immediately to prevent the disease spreading.
Red Spider Mite – Causes leaves to look rusty. Remove and burn affected leaves.
Whitefly – Can cause significant problems with mould. Use organic or inorganic (but vegetable safe) pesticides. |
How to Grow Greenhouse Cucumbers – Ideal Cucumber Growing Conditions
Cucumbers are one of the most commonly grown crops in the world, from commercial greenhouses to small gardens. As a part of the cucurbit, or gourd family, cucumbers grow great outdoors, in row covers, and in controlled environments. Growing cucumbers in greenhouses lets growers extend their growing season, and produce larger, higher quality yields.
Cucumbers are a warm weather crop. Outdoors, growers usually plant cucumbers during spring time, once the danger of frost has passed. This allows the plant to flower and produce fruit in relatively warm temperatures, including soil temperature.
Greenhouse cucumber production can be year-round, depending on the level of control in the space. Cucumbers enjoy stable conditions and are susceptible to low temperatures and fluctuations in humidity. For optimal production, it’s important to avoid these two pitfalls.
What Are the Optimal Cucumber Growing Conditions?
There are numerous benefits to growing cucumbers in a greenhouse. You can provide the best conditions throughout the entire grow cycle. This ensures higher quality produce, larger yields, and lower rates of disease, molds, and pests.
Different varieties of cucumbers may have slightly different requirements. However, this guide should cover the basics for most common cucumber strains.
As a vining plant, cucumbers grow well both in soil and in a soilless environment. When planting in soil, it’s best to use a fertile soil, with a soil pH level of 5.5 to 6.8. Cucumber plants also need consistent watering. Under ideal conditions, you should water the soil with around an inch of water per week.
What Is the Ideal Temperature for Greenhouse Cucumber Production?
Maintaining the right temperature levels is one of the most basic greenhouse functions. Growing in a closed or semi-closed environment allows you to heat or cool as necessary and retain the right temperatures.
Like all crops, cucumbers too have a preferred temperature range. As a warm season crop, the ideal temperature range for cucumbers is generally 21-26°C. However, the plants can withstand a wider range, if necessary, ranging from 15-29°C. Like in nature, daytime temperatures may be higher than nighttime.
It’s important to note that cucumber plants are sensitive to frost. Low temperatures may cause frost damage, leading to wilting.
When it comes to cucumber germination, the ideal temperatures should be within the range of 15-29°C. Soil temperatures should be around 21°C, or higher, for germination to succeed. In general, germination occurs slower in lower temperatures.
Ideal Temperatures for Cucumber Cultivation:
Vegetative growth and fruit setting – 21-26°C
Seed germination – 15-29°C
What Is the Ideal Humidity for Greenhouse Cucumber Production?
Humidity is a major cultivation factor for any crop. Like temperature, every plant has its own ideal relative humidity or VPD range. Too high, or too low humidity can lead to several problems. It impacts growth, the plants’ ability to set fruit, and may lead to various disease or mold outbreaks.
In low humidity, plants experience stress due to heightened evaporation rates. This may lead to the plants significantly slowing down physiological processes, in order to retain water. So, when humidity is low, plants will struggle to grow and produce fruit. Low humidity may also increase susceptibility to various pests and diseases.
High humidity is generally favorable for growth. However, when humidity is too high, it can limit the plants’ ability to transpire, in turn slowing down growth as well. High presence of moisture can also lead to various diseases, including botrytis and powdery mildew.
Relative humidity may also have an impact on pollination and fruit setting. It can cause the pollen to dry out or be too damp. Cucumbers require the male flower to pollinate the female flower, so effective pollination is necessary.
Cucumber plants prefer a comfortable relative humidity range. However, they’re sensitive to fluctuations, so controlling humidity and providing consistent conditions is important.
The ideal relative humidity range for cucumbers is 60-70% RH. During nighttime humidity may be higher – 70-85% RH. In terms of VPD that’s 0.75-1.35 kPa during the day, and 0.35-1 kPa overnight.
Ideal Relative Humidity for Cucumber Cultivation:
Daytime – 60-70% RH
Nighttime – 70-85%
Optimal VPD for Cucumber Cultivation:
Daytime – 0.75-1.35 kPa
Nighttime – 0.35-1 kPa
How to Maintain Optimal Humidity in Cucumber Greenhouses
In any closed horticulture setting, humidity will inevitably rise to 100%. This is due to the plants’ transpiration.
Cucumbers are no different. Without removing moisture from the greenhouse, you will experience high humidity and water condensation. These lead to various diseases, mildews, and overall inefficient growth.
Traditionally, growers would reduce humidity by opening the greenhouse windows and vents to let the moisture out. This may be effective sometimes, but not always. It’s also highly inefficient, in terms of energy, as it allows heat to escape as well.
So, the most effective and efficient way to control greenhouse humidity is by using active dehumidification, such as DryGair.
To successfully control humidity, it’s also important to understand what affects it. For example, radiation, or lighting, can increase evaporation and transpiration, pushing humidity upwards. Higher temperatures will also increase the absolute humidity in the space, which can be dangerous when temperatures fall in the evening.
Using Air Circulation to Improve Humidity Control
Airflow is a great addition to dehumidification, and can help ensure ideal humidity levels for your cucumber plants. Air movement through the foliage helps disperse local pockets of humidity, known as microclimates. This is especially useful in dense or overlapping foliage, as moisture can easily get trapped.
Air circulation is a specific type of airflow. It’s non-linear, meaning it doesn’t just blow air in a single direction. Rather, it disperses air from the center of the space, in all directions, 360°. This creates a circular air pattern that ensures uniform conditions everywhere in the greenhouse.
All DryGair dehumidifiers come equipped with a patented air circulation mechanism, in order to provide total humidity control.
Additional Tips for Cucumber Greenhouses
Keep the Greenhouse Clean
It’s important to note that not all diseases are related to environmental conditions such as humidity or temperature. For example, cucumber bacterial wilt is often associated with pests, such as cucumber beetles, rather than environmental conditions.
You can help prevent many issues by keeping a clean environment. For example, organic matter on the soil is a hotbed for bacteria and pests. So, routinely removing any dried leaves and debris from the greenhouse can go a long way in preventing many common issues.
Use Thermal Screens to Retain Heat and Save Energy
Cucumbers prefer a warm environment. So in most cases, you need to heat the greenhouse to provide the ideal temperatures. However, heating can be very energy intensive and is associated with high costs.
Installing thermal screens is one of the most effective ways of retaining heat in the space, thus needing much less heating. Combining two or even three screens can drastically increase this effect.
One thing to note when using screens, is that humidity may build up in the closed space. However, using dehumidifiers solves this issue. It allows you to keep the greenhouse closed, retain heat, and maintain ideal humidity levels, all from inside the space.
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Level 1: Cucumber seed germination
Zucchinis are real summer vegetables. The seeds only germinate above 20°C. The seedlings are sensitive to lower temperatures.
So, sow them indoors around the end of April/beginning of May. That's called pre-sowing. When the plant is big enough, you can move it into your garden box at the end of May.
There's one step before you pre-sow: let them grow a root first. That's called pre-germination or pre-sprouting.
If you pre-sprout your seeds you can be sure your seedlings will grow well. And you want to be sure: these zucchini seeds aren't cheap. Why risk it? 😉
Here's how to pre-sprout: get a piece of paper towel moist, fold it in half, put the seeds in between the 2 layers, and you're done.
Level 2: Put the pre-sprouted seeds in pots
Next, you're ready to pre-sow. Here's what you need:
pre-sprouted seeds
2 MM-Airpots
vermiculite
MM-Mix
Fill the 2 air pots with equal parts vermiculite and MM-Mix.
This half-half mixture is ideal because seedlings don't need a lot of nutrients yet. The MM-Mix alone is too rich. Too many nutrients and they'll grow too fast: the plants become limp instead of sturdy. The vermiculite also helps retain moisture.
So, make the mixture nice and damp. Put 2 seeds in each air pot. Be careful: you don't want the root to break off.
Then put the pot in a bowl or saucer, give it some water, and put it in a warm place on the windowsill.
Level 3: Cucumber seedlings
When you see the first seedlings, you know it's going well. They probably won't all come up at once, but give it another week.
After they come up, put the air pots in the lightest spot you have, but ideally not too warm.
Give the air pots a quarter turn every day to prevent the seedlings from growing crooked. Keep the mix moist.
In 5 days or so they'll be ready for the next level.
Level 4 and 5: Taking care of your plants on the windowsill
Keeping plants happy on the windowsill is tricky. Make sure they get plenty of light and are not too warm. So, full sun, but not warmer than 20°C.
Give the pots a quarter turn every day to prevent crooked plants, and keep the mix moist.
Level 6-10: Getting used to the outside air
Around the second half of May, let the plants get used to the outside air: a little longer every day.
At level 10, your plants spend all day outside (or in greenhouse with open doors for the feel of being outside) and only come inside at night.
Level 11: Plant the 2 best plants in your garden box
Once they have gotten used to the outdoors, choose the 2 most beautiful plants and transfer them to your garden box.
Choose a patch in the back row near the trellis. Make a hole, sprinkle some MM-Plantfood in it, and put the plants inside.
Level 12 and 13: Care and the trellis
For these levels, it probably won't be very warm yet and the plants won't grow very fast at first.
As soon as they reach the trellis, weave the stems through it. Use string or binders if needed.
Levels 14: Flowering and side branches
Cucumbers flower on their side shoots. That's where the cucumber fruits will soon grow.
Side shoots cost your plant a lot of energy. Cut them back so they're only 10 cm: just after the 2nd flower. You can find a full how-to guide with photos here.
Cucumber fruits grow very quickly after they're fertilized. From flower to harvestable fruit can take as little as 10 days.
Keep an eye on them and harvest soon: snack cucumbers taste best when they're 10 - 15 cm long.
Level 15: Adding extra nutrients
By July, the cucumber plants will need more nutrients to feed all the fruits growing on them.
So add a scoop of fresh nutrients at the foot of the plants. You'll harvest a lot of cucumbers in the coming weeks.
The last levels
End of August and the days are getting shorter. The leaves on your cucumber plants turn yellow and brown, and just don't look as nice.
It's no big deal. If the stem continues to grow, then the flowers and cucumbers keep growing too.
You can keep harvesting until it gets really cold, around the beginning of October. Then it's time to say goodbye to your plants and take them out of your garden box or MM-Mini. |
Tips for growing cucumbers in greenhouse
1. The right species of cucumber for greenhouses
If you want to grow cucumbers (Cucumis sativus) in a greenhouse, you should opt for salad cucumbers. With their smooth skin, they are specially developed for cultivation in greenhouses. Salad cucumbers generally only form female plants and are self-pollinating. Stores offer varieties that are resistant to diseases like leaf spot and have a high resistance to powdery mildew. Young plants that have been grafted on pumpkin plants are equally robust and ideal for greenhouses.
2. Sowing and Planting
You can sow cucumbers in heated greenhouses from March/April, but in unheated greenhouses you should wait until May. The seeds need evenly moist soil and a constant temperature of 68 degrees to germinate. As soon as the first seed leaves (cotyledons) appear, you can remove the weaker young plants, leaving only the strongest cucumber plants. When they are between 8 and 12 inches tall, they can be put in their final location in the greenhouse with a distance of around two feet between each plant. Grafted cucumbers should be planted so that the grafting site is a finger’s width above the soil. Since cucumbers prefer nutrient and humus-rich soils, it is important to enrich the soil with mature compost before planting. Cucumbers can also be planted in large tubs. Lightly earthing up cucumber plants promotes the development of adventitious roots.
3. Light and water in the greenhouse
Cucumbers are heat-loving plants that need light to thrive. However, if the sunlight is too strong – especially during hot days – the plants should also be provided with some shade in the greenhouse. Putting shade cloth or nets on the glass roof protects the plants from direct sunlight, as do shade-giving neighboring plants like tomatoes.
Cucumbers require plenty of water and need to be well cared for in the greenhouse. It is therefore best to water the root area thoroughly in the morning, and with lukewarm water. In order to avoid fungal diseases, the leaves should be kept dry or be able to dry off well. A layer of mulch ensures that the soil is evenly moist and does not dry out too quickly. When the fruit develops, it can be fertilized weekly with a liquid fertilizer – one cucumber plant needs around one liter of a nutrient solution containing organic liquid fertilizer.
4. Make sure that the greenhouse is well ventilated
Although it is important for cucumbers to have a relatively high humidity in the greenhouse, they do need a bit of fresh air from time to time. This prevents fungal diseases like downy mildew. Open the doors and windows of the greenhouse regularly in the mornings and evenings to let some cool air in.
Using string makes it easier for the cucumbers to climb
Cucumbers should be grown on climbing aids both in open ground and in greenhouses. You can use scaffolds, trellises, or even sturdy string to guide the plants upwards. This keeps the fruit away from the ground, ensuring it is better ventilated and easier to harvest. The string should be tied to the roof structure or a support wire. Spiral the cucumber plants around the stem and wrap the shoots around the string once or twice a week until they reach the holder. Tip: Trimming the side shoots behind the first flower ensures strong plants and plenty of fruit. |
Ideal Greenhouse Environment
Climate Conditions: Cucumbers demand very stable climate conditions. The ideal humidity should be around 60% to 70% during the day and higher at night. While maintaining precise temperatures is necessary in order to optimize the production of cucumbers, there is a relationship between temperature and light, even though cucumbers can grow with less than 12 hours of light.
Soil: It is important to have a good media/soil depth; the recommended pH range for good plant development is 5.5 to 6.8.
Humidity: Careful management of humidity in the greenhouse is an important part of maintaining both crop production and crop health. Humidity can influence everything from plant growth rates to disease problems. Cucumbers perform well under conditions of high relative humidity.
Watering: In low humidity conditions, water supply is critical. Cucumbers grown at lower relative humidity conditions require a lot of water, and water shortage causes misshapen fruits, abortion, or less vigor to sprout secondary shoots. It is very important to ensure the availability of water, especially after the beginning of harvesting.
Pests and Diseases: Greenhouse humidity also impacts the presence of pests and diseases. If leaf surfaces become wet from drops, condensation, or misting, the risk of infection increases. Good cucumber disease management should include crop hygiene practices, rapid positive diagnosis of any unfamiliar or unusual plant symptoms, and routine monitoring and treatment. |
SUSTAINABLE CUCUMBER CULTIVATION
Greenhouse cucumber plants grow at a rapid pace, with fruit production starting 60 to 70 days after seeding. The temperature should range between 24°C and 26°C, and while higher brief daytime temperatures can be tolerated, prolonged heat is a quality risk. Greenhouse cucumbers can be grown at much lower temperatures to save on heating costs, but because it slows the growth rate and lengthens the production cycle, it may not be a viable option for some growers.
This crop is grown both in soil (well-drained and low in soluble salts) or in a soilless growing medium such as peat-lite (a mixture of sphagnum peat and vermiculite or perlite) or sawmill by-products (mixtures of bark, wood chips and sawdust). Greenhouse cucumbers can also be grown hydroponically.
For soil cultivation, growers add potassium, phosphorus and nitrogen before planting, and the soil should also be tested ahead of planting for pH and micro-mineral levels. If a deficiency of a minor mineral becomes apparent during crop growth, plants can be treated with foliar applications.
The use of manure is feasible but must be managed closely in terms of soil salinity.
In soilless cultivation, a nutrient solution is applied in every irrigation cycle using different irrigation systems, for example through drip irrigation tubes.
There are two viral pathogens, cucumber mosaic and watermelon mosaic, that are serious threats. Aphids can transmit mosaic viruses from other susceptible crops and weeds from outside the greenhouse. Powdery mildews (Sphaerotheca fuligenea) are also a problem, but resistant varieties are available. Gray mold (Botrytis cinerea) infections can appear when humidity is not properly controlled. Infections of Pythium sp. can occur in cucumber plantings, known as ‘post-emergence damp-off.’
Crooking (excessive curving of the vegetable) can arise due to a variety of factors but humidity, temperature extremes and lack of proper fertilization are believed to be contributors. Insects that can jeopardize greenhouse cucumbers include white flies (Trialeurodes vaporarium), two-spotted mites (Tetranychus urticae), vegetable leaf miners (Liriomyza sativae), cabbage loopers (Tricoplusia ni), and greenhouse thrips (Heliothrips haemorrhoidalis).
Pythium, commonly referred to as water molds, can cause serious infections for many greenhouse vegetable crops, including cucumbers. An infection of Pythium can result in significant crop losses if not treated and several species of Pythium can lead to “damping-off in seedlings and crown and root rot in greenhouse cucumber, pepper and tomato crops,” according to the British Columbia Ministry of Agriculture, Food and Fisheries.
AGTECH SOLUTIONS FOR CUCUMBER GROWERS
Growers are looking for ways to reduce their inputs, especially with the rise of sustainable agriculture practices which focus on reducing water, chemical pesticide, and fertilizer use. Sustainable, chemical-free methods of controlling disease, increasing fertilizer uptake efficiency, and improving irrigation water efficiency are now available with AgTech.
Besides new innovative technologies that are automating harvesting and packing processes and AI systems that better control the growing environment, there are also AgTech solutions that enhance irrigation water. The injection of nanobubbles into irrigation water is emerging as a superior water treatment method that prevents and reduces pathogens such as Phytophthora and Pythium through the unique chemical and physical properties of nanobubbles.
Quality irrigation water is imperative for large-scale cucumber plant and root health as well as crop production. Greenhouse growers often reuse irrigation water from source water basins, resulting in decreased irrigation water quality over time, including decreased dissolved oxygen and increased bacteria and algae growth. Without oxygen present in the root zone, plants cannot take up nutrients and water from their roots leading to poor plant and root health and low cucumber crop production.
When nanobubbles are created using oxygen, they supersaturate the water with dissolved oxygen at a sustained high level. Supersaturated levels of dissolved oxygen (DO) in the water will improve the availability of oxygen which consequently reduces root pathogens, improves root growth and health leading to enhanced nutrient absorption. All this can be achieved relatively quickly and cost-efficient when using an oxygen generator that produces oxygen with 93% purity and a technology that transfers gas into water with an extremely high 85% efficiency.
Green Circle Farms in Leamington, Canada, reported high levels of Pythium in their seven-acre cucumber and pepper greenhouse. After implementing Moleaer’s nanobubble technology, they noticed suppressed disease resulting in reduced chemical treatment costs. Green Circle Farms also noted nanobubble enriched irrigation water led to better root health, improved plant vigor and increased crop yield.
In addition to increased dissolved oxygen levels, nanobubble’s unique properties have added benefits to enhance irrigation water for cucumber growers. When nanobubbles come in contact with contaminants, they collapse producing hydroxyl radicals, a highly effective oxidant, that lyses bacteria cells, breaks up biofilm and algae, and reduces pathogens. Nanobubbles also improve irrigation water quality by reducing its surface tension which increases soil moisture and nutrient uptake as the water is held near the root zone longer. This has helped cucumber growers improve fertilizer efficiency by improving mixing in fertigation tanks to reduce fertilizer runoff and loss from leaching as well as creating improved conditions at the root zone to increase plant nutrient uptake efficiency.
Demand for fresh indoor-grown greenhouse cucumbers, and greenhouse food production in general, will continue to increase. Greenhouse growers must use every tool at their disposal, including innovative technologies, to prevent disease and ensure high-quality yield through super-high root oxygenation and the unique properties of nanobubbles and other aspects of production that support plant health and vigorous growth. |
What to consider when growing cucumbers
Selecting the perfect variety: Before you start planting cucumbers in your garden, it's essential to choose the correct cucumber variety that suits your preferences and the climate. Here are some popular cucumber varieties to consider:
Outdoor varieties: These cucumber varieties are best suited for the UK's unpredictable weather. 'Marketmore' and 'Bush Champion' are excellent choices. They thrive in outdoor conditions and are known for their reliability.
Greenhouse varieties: If you have a greenhouse, you can also opt for varieties like 'Mini Munch' or 'Telegraph Improved.' These varieties require a more controlled environment and can be grown successfully with the help of a greenhouse.
Soil preparation: Cucumbers thrive in well-drained, fertile soil with a pH level between 6.0 and 7.0. To prepare your garden soil for cucumber planting:
- Start by clearing the area of any weeds or debris.
- Incorporate organic matter like compost or well-rotted manure into the soil to improve its fertility.
- Ensure good drainage by adding sand or perlite if your soil is heavy.
Sowing cucumber seeds: When it comes to starting your cucumber garden, the process begins with sowing the seeds. This crucial step sets the foundation for healthy, thriving plants later on. Selecting the right seeds, preparing the soil, and timing the sowing are all key considerations for a successful cucumber crop.
Cucumbers can be grown from seeds or transplants. If you opt for seeds, you can start them indoors in late winter or early spring (February to March) and here’s how:
- Fill small pots or seed trays with good quality seed compost.
- Sow cucumber seeds about 1 inch deep and water lightly.
- Place the pots or trays in a warm location with plenty of sunlight or use a heated propagator.
- Once the seedlings have two true leaves, transplant them to larger pots or directly into garden soil.
Planting cucumber transplants: For those who prefer to start with transplants, you can purchase young cucumber plants from garden centres. Planting transplants is relatively straightforward:
- Wait until the risk of frost has passed in late spring or early summer (usually May).
- Dig planting holes in your garden soil, spacing them about 18 inches apart for bush varieties and 24 inches apart for vining varieties.
- Carefully remove the young cucumber plants from their pots and place them in the holes, ensuring the top of the root ball is level with the soil surface.
- Water thoroughly after planting to help the transplants establish.
Providing the proper care: Growing cucumbers requires regular care to ensure a healthy crop. Here are some essential care tips:
Watering: Cucumbers are thirsty plants. Keep the soil consistently moist, especially during dry spells. Water at the base of the plants to avoid wetting the foliage, which can lead to diseases.
Feeding: Feed your cucumber plants every two weeks with a balanced liquid fertiliser, rich in potassium and phosphorus, to encourage fruiting.
Support: If you're growing vining cucumber varieties, provide support like trellises or stakes to keep the vines off the ground and prevent rotting.
Mulching: Mulch the soil around your cucumber plants with organic materials like straw or compost to retain moisture and suppress weeds.
Pest and disease control: Look out for common pests like aphids and cucumber beetles. Applying natural remedies like neem oil or releasing beneficial insects can help control these pests. To prevent diseases, ensure good air circulation around your plants.
Harvesting: The excitement of harvesting your cucumbers is a reward for all your hard work. In the UK, cucumbers are typically ready for harvest 8-12 weeks after planting. Here's how to know when they're ready:
- Cucumbers are best harvested when they're still young and tender. They should be firm, green, and about 6-8 inches long.
- Use a sharp knife or garden scissors to cut the cucumbers from the vine, leaving a small stem attached.
Harvest your cucumbers regularly to encourage continuous fruiting throughout the growing season. If you notice any overripe or yellow cucumbers, remove them promptly to encourage new growth.
Storing: Once you've harvested your cucumbers, you'll want to store them correctly to maintain their freshness. Here are some storage tips:
- Cucumbers can be stored in the refrigerator for up to a week. Place them in a plastic bag to retain moisture.
- If you have an excess of cucumbers, consider pickling them or making cucumber salads to enjoy their flavour all year round. |