to mature in the plug flat and the large grade about one week less than the medium grade.
Potting and Finishing
The majority of African Violets are potted and finished in 4-inch pots, though 4½- and 5-inch pots are not uncommon. During potting, care should be taken not to plant the plugs too deep and that patented cultivars are properly labeled. Once potted, the plants can be maintained on the bench, pot-to-pot, for 5 to 6 weeks. Optimum light, temperature, and other cultural practices are important at this stage for a vigorous uniform crop. When flower buds begin to poke up through the leaf canopy, plants can be placed at a final spacing of four pots per square foot on capillary or ebb-and-flow benches. African Violets are usually shipped when 5 blooms are open depending on the desire of the market. This will usually occur 5 to 6 weeks after spacing. The total production time from leaf cutting to a finished 4-inch pot is 32 to 36 weeks depending on the time of year and geographic location.
The schedule in Figure 1 is a generalization. Individual stages may require more or less time depending on the cultivar, time of the year, and geographic location.
Figure 1. Production stages and timing for scheduling African Violets in 4-inch pots.
The most important consideration for a disease-free crop lies with sanitation of all pots, flats, benches, medium, and any other articles coming in contact with the plants. General greenhouse cleanliness is a must! This is especially true where "crown rot" (Pythium/Phytophthora) is concerned. Other factors in disease prevention are: obtaining healthy transplants, keeping plants growing vigorously, the correct environment, and carrying-out production stages on time. Fungicide treatments come and go, but it is easier and less expensive to prevent disease problems rather than cure them. Powdery mildew can be a problem during changeable weather. This can be controlled by burning sulfur and modifying the environment to keep the foliage dry. Botrytis is best controlled by reducing the humidity.
Greenhouse cleanliness and isolation of new incoming material can go a long way toward preventing insect problems. The major insect pests of African Violets are foliar nematodes, thrips, mealy bugs, and cyclamen mites.