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Some vegetables, such as lettuce and corn, have especially sparse, less developed root systems. Other crops, such as pepper and tomato, have fibrous root systems that more effectively remove water from a given area of soil.
Cool-season vegetables, those planted in spring or fall, generally root to a shallower depth than warm- season and perennial vegetables. More frequent watering may be needed in stressful periods for these crops. Because fall and spring are usually characterized by cooler temperatures and more abundant rainfall, watering during these times is usually of less concern.
In many direct-seeded crops, you must be sure that adequate water is available in the root zone to encourage germination of seeds and allow for initial growth and development. Thus, it is often necessary to provide frequent shallow waterings during dry seasons until the crop develops beyond the seedling stage. This is especially true of crops planted for fall production.
With transplanted garden crops, providing water at transplanting time is essential to support the plant until it is able to absorb water from the surrounding soil. In general, apply ½-1 cup of water with each transplanted vegetable. Water slowly so that it soaks into the area near the plant, or water at the bottom of the transplanting hole.
A garden crop needs water throughout its life cycle to survive and grow. There are several periods, however, when adequate water is critical.
Stage Crop
Germination, Seedlings--especially summer and fall crops
Pod enlargement--Beans, peas
Head development--Cabbage, broccoli, cauliflower
Root enlargement--Carrot, onion, potato, radish
Flowering to early fruit set--Corn, cucumbers, squash
Early fruit development--Melons
Uniform all season--Tomatoes, peppers, eggplant
During these periods, the plant may respond to a lack of water by changes that are
irreversible during the remainder of its life. See table below.
Methods of applying water
The most popular methods of applying water to the root systems of garden crops are flood, sprinkle, and drip/trickle.
Flood--Many garden crops can be watered by "flooding" or applying a flow of water to the soil surface. This can be done by using a trench or basin near each plant or by running water down a furrow alongside each row.
This method works best in medium-textured soils that are fairly level. Water must flow from one end of the garden to another and must soak into the soil slowly in order to continue to flow in the trench.
Crops are usually planted in a raised bed when using this method so that water runs alongside the bed or row, not down the row itself.
Sprinkler--The sprinkler is by far the most extensively used watering method in home gardens. A sprinkler is inexpensive and can be used to water a diversity of crops in a small area. Distribution of water applied by sprinklers should be considered because more water is usually delivered to the center of the sprinkled area. Placing a few cans in the area to check for uniformity of water application will give you an idea of the pattern of your sprinkler.
One of the disadvantages of sprinklers is that they allow a considerable amount of water to evaporate into the air. Using coarse droplets and lower water pressure can reduce evaporation losses, especially on hot, windy days. Watering in cooler, less windy periods also helps.
When sprinkling garden crops, be sure to apply water in a way that allows plant foliage to dry as soon as possible after watering. Thus, early morning and early evening watering is preferable to late evening watering.
Drip/trickle irrigation--This method of watering is designed to keep a portion of the root zone well supplied by applying water on a daily or every- other-day basis. Drip or trickle tubes are usually laid to the side of the row or between two rows. To wet a continuous strip of soil, required by most vegetable crops, you should have a hole or "dripper" in the line every 10-12 inches. Many drip tapes come with the holes at prepunched intervals. Other types of drip tubing are designed to leak over the length of the tube.
Drip systems are usually operated at low pressures (5-15 PSI) and usually require from 1-3 hours a day to supply the water lost from the crops during stress periods. Because of the danger of clogging the small pores of drip tape, water filtration is essential for this system. Most garden center dealers have drip irrigation kits with filters, pressure regulators, and water distribution lines. Most can offer assistance in design and layout of a drip system.
At the end of the garden season, the system can be flushed, dried, and stored in a protected location for next year. It may be necessary to replace thin drip tubing each year. Thicker tubing may last for several seasons. Use care in hoeing near drip tubing and avoid walking on it. These activities may punch holes that interfere with the normal slow dripping of the tape.
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