Most garden plants need about an inch of water a week, which comes out to a three-quarter of a gallon per square foot. You can give that water in one shot, once a week, or in small doses, say one-seventh of an inch each day. For the benefit of your plants, you’ve got to be consistent in whatever watering schedule you choose. Of course, who’s going to remember to go out every single day to give all their plants just a little water? Hence the traditional recommendation to water deeply and infrequently.

Enter “drip irrigation,” an automated method of delivering water to plants in small doses. Small doses of water promote shallow rooting, so you may wonder what the advantage of drip irrigation is. Well, shallow rooting is beneficial because most of the feeder roots of plants live near the surface of the soil. Why? Because that is where nutrients, air, and biological activity are most concentrated.

Drip irrigation also uses water very efficiently. When you flood the soil once a week around a plant using a sprinkler or watering can, you fill up all the soil pores. But plant roots need air to function, so do not begin to drink up any water until gravity drains enough water out of the soil to leave some air spaces. Then, the plant draws on water still clinging to soil particles by capillary attraction. But that first water that drained away was wasted. Drip irrigation supplies water gradually, the way plants drink it up, with roots always working at their best because the soil never need be flooded.

TIMED CONVENIENCE

One of the most important components of my drip irrigation system is a water timer, which automatically waters my garden every day through the summer. The timer is inexpensive, operates on a battery, and threads right onto my hose spigot. I set the timer to turn the water on six times a day, but for only a few minutes each time, just long enough to deliver a total of one-seventh of an inch of water each day.

Before the water makes its way out to my garden, it also passes through three other items attached to the timer. These items are: a backflow preventer, which keeps water running in one direction only (to prevent siphoning in case of a pressure drop); a filter; and a pressure regulator. Drip irrigation operates at low pressure, so inexpensive, low pressure fittings can be used and minimal demands are made on household water.

OUT TO THE GARDEN

The water is carried out to, and through, my garden in half-inch, black plastic pipe, which can be buried if desired. Once out in the garden, water is dripped to plants via “emitters” that plug into this tubing. Wherever I have a continuous row of plants—carrots or other vegetable plants, for example—I plug in a special tube that drips out water at closely spaced intervals along its length, then run that emitter tube along the row of plants. For my blueberry shrubs, each spaced seven feet apart, I run the half-inch pipe along the row of plants, then plug in a couple of individual spot emitters next to each plant.

These emitters, whether tube or spot emitters, are more than just leaky pieces of plastic. The best of them are technological marvels that consistently put out a specified amount of water even if water pressure changes. They also have little flaps or channels for swirling water around and preventing the tiny orifices from becoming clogged with any debris that might enter the line. Most emitters can be buried, but mine are on the surface of the ground so I can periodically check up on them.

If you can now picture in your mind your garden watered by drip irrigation, you might also “see,” in that picture, some other advantages of this system. Fewer weeds, for example. Drip irrigation puts water precisely where you want it, so you’re not promoting weeds and wasting water on paths or bare soil, both unavoidable with a sprinkler. And because plant foliage remains dry with drip irrigation, chances for diseases are minimized.

Rain rarely falls as soon as a plant needs water, so even in a wet summer, plants grow better with timely watering. And in a dry summer -- well, the effect of watering is dramatically obvious. My corn, which grows eight-foot-high stalks even in dry years, is testimonial to the benefits of drip irrigation.

Lee Reich, PhD (leereich.com) is a garden and orchard consultant; he hosts workshops at his New Paltz farmden, which is a test site for innovative techniques in soil care, pruning, and growing fruits and vegetables.