The Association of Master Gardeners and the University of Arizona Yavapai County Cooperative Extension hosted a Zoom workshop on backyard vegetable garden irrigation on Tuesday, July 25.
Led by master gardener Bill Maynes, the workshop explained the importance of irrigation, different types of irrigation, and choosing the right irrigation system for your garden.
Maines defined irrigation as the art and science of applying the proper amount of water needed to keep plants healthy and produce good crops. He argued that irrigation is particularly important in the dry climate of the west, where rainfall is often low and the dry season is long, adding that most vegetable crops are drought-tolerant.
Vegetable plants need about an inch of water per week, and ideally after each watering, the soil should stay moist right up to the root system, says Maines. During the summer, he often needs 2-4 waterings a week, with deep-rooted and shallow-rooted plants having different watering needs. Keeping soil moisture even has many benefits, including reduced soil crusting, prevention of premature ripening, improved germination, reduced wilting, consistent growth, and increased fruit size.
Mains also described different types of irrigation systems. Manual irrigation involves manually watering plants using a cup, watering can, or shower nozzle. This is easy and cost effective, but can be difficult in large gardens or during the summer.
Furrow irrigation is often used for agricultural purposes such as furrowed rows, berry vines and fruit trees. Equipment costs are low because only long hoses are required, but in hot climates this method produces a lot of evaporation. Basin and berm irrigation can be used to create small moats around plants.
Micro-irrigation, including drip irrigation, spitter irrigation and bubbler irrigation, is the most efficient form of irrigation currently in use. Drip irrigation uses plastic tubes to water the topsoil infrequently and frequently to maintain optimal soil moisture availability in the root zone. Soaker hose irrigation is a form of drip irrigation and works best if your garden has short rows of plants that are 20 to 25 feet long. These systems deteriorate faster than true drip irrigation systems.
Advantages of drip irrigation include more efficient water use and reduced water loss through runoff, while its disadvantages include the cost of equipment. Maynes argued that the benefits outweigh the drawbacks. He added that factors to consider when choosing an irrigation system include budget, garden size, soil type and plant type.
