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A common mistake among gardeners new to the desert is to water often and shallowly. Deep watering encourages vigorous deep root growth early in the season, which helps discourage water stress later in the season. Deep watering is accomplished by slowly flooding an area and allowing it to soak deeply into the soil profile. This also helps to flush out salts and prevent salt buildup. There is no standard guide to how often watering should be done in desert gardening. The best method is to simply watch the plant. Water stress is typically detected by leaf wilting. Some wilting is common during the day, even in well-watered plants. If plants do not recover overnight from day-time wilting, then they are likely in need of water.
A common misunderstanding is that ‘drought-adapted’ or ‘aridlands’ crops don’t need much water, as evidenced by the fact that they grow in drought-prone or arid areas. Even within these areas, most crops are grown during the rainy season, however scarce it may prove to be in any given year. ‘Drought-adapted’ or ‘drought-tolerant’ doesn’t mean a crop prefers to grow under drought conditions. Rather, it means a crop might survive some drought conditions where other, more conventional crops might not. Don’t be fooled, plants require sufficient water, nutrients and light to produce healthy seeds, regardless of whether they are considered ‘drought-tolerant’ or not. Some plants, such as tepary bean and black-eyed peas, are not tolerant of soggy soils. When their roots are submerged in standing water for days on end, their leaves often turn yellow and drop, a symptom that also occurs under conditions of insufficient water!
Plants need nutrients. Addition of compost and well-aged manures, as well as green manures and cover crops, are good ways of maintaining soil nutrient levels and adding organic matter, which continues to break down slowly over time. These are best added before planting. Mid-season fertilizers are easily accomplished with fish emulsions or manure or compost teas. Not all plants have the same fertilizer requirements, so check before you apply broadly.
Mulching is a necessity for desert gardeners as it greatly reduces evaporation and keeps soil temperatures lower. Spread straw, hay (may contain more weed seeds than straw), leaves, or other organic matter as a layer about 3 inches thick over beds. Replenish during the season as needed. Seasonal weeds can also be used for mulch as long as they are pulled before producing seeds.
Sooner or later, most gardeners face the challenge of insects or disease. The best insurance against both are to maintain healthy, living soils and keep plants well nourished and watered. Healthy plants are better able to ward off insects and diseases. Diseased plants should be removed immediately, as many diseases spread easily and quickly among plants. For some, there are organic remedies. Many insects can be easily removed by hand while others may require the use of insecticides. For a list of organic insecticides, check the OMRI website. Encouraging beneficial insects or using plants that repel/attract insects (companion planting) are also helpful ways to minimize damage from insects. For more information on companion planting, visit ncat.org.