The best choice of watering methods for a vegetable garden depends on the design and size of the garden.
When the garden is small, watering with a hose in early morning is a pleasure. You have time to philosophize over sprouting seeds and rejoice in the almost measurable growth of young vegetables. But as simple as it seems, hand watering takes considerable practice to know how long to water. The best way to learn is to water until you think you’ve watered enough, wait a few minutes for the water to sink in, then dig a hole with a trowel to see how deep the water has gone.
Garden centers offer a large variety of moderately priced hose-end sprinklers. There are rotating-head sprinklers, square or round chambers that shoot jets of water in various patterns, the oscillating-arm type that project a steady stream back and forth, and the spike variety that squirt large and small drops in an arc or circle. The best are usually the simplest, because nothing can break or fail to do what it is supposed to do.
A system of in-ground sprinkler heads that pop up and water a predetermined area at the command of an electric timer is the most elegant and refined system (and also the most expensive).
Plastic pipes conduct the water to the heads. If you are planning to rototill, do not put sprinkler heads within the garden area. Install them around the garden perimeter, and design the system so the watering patterns overlap slightly.
Soaker hoses leak along their entire length. They are usually made of recycled tires. The lengths are joined with hose couplings so you can create a network that covers the garden from one water source. They are laid along rows of vegetables or snaked through intensive plantings. Seeping water into the soil very slowly, they don’t ever cause runoff or overwater.
Soaker hose systems are easiest to position before planting—place the hose where the plants need them, before growth starts in spring and the annuals are planted. If your garden is mulched, put them under the mulch.
Soaker hoses don’t water evenly from one end of the hose to the other, especially if they are on a slope. They lose pressure with distance from the water source, or when pulled by gravity. Use them on flat ground, and keep the runs as short as possible.
Drip Irrigation Systems
In this type of system, water flows through a filter and a pressure regulator into a network of pipes studded with emitters. The emitters, which deliver water drop by drop, may be positioned so they water one or more plants. Water moves through the soil to a distance of about 1 foot from the emitter. The systems can clog and need to be checked occasionally. They usually are controlled by a timer to water for several hours a day.
A drip emitter system is custom-designed to meet the needs of each plant in the garden. The easiest way to begin is with a kit, which will contain all the essential parts, then add to the system as necessary.
In dry regions, very large gardens planned for row-crop growing often are watered via a network of shallow, narrow furrows which are flooded by hoses as needed. The furrows are dug the length of the planting rows, 5 or 6 inches from the plants and to a depth calculated to bring the water to the root systems. The furrows must angle slightly downhill to enable the water to flow to the end of the row; but an angle that is too steep deprives the upper part of the row of its share of water. The space left for paths must be wide enough to accommodate both the furrows and the gardener.