Water should be supplied to the garden either by overhead sprinklers, or by a system of tubes that drip or ooze water at the base of the plants. Each method has its benefits and its problems. Overhead watering is what most people in the East think of when you mentioning watering, but in the water-hungry West since the development of the plastics industry over the past twenty years, on- or under-ground irrigation has become very common, especially in mild areas where the ground doesn’t freeze solid in the winter. Drip-and-ooze systems are very efficient in terms of water use; but unless you bury the pipes eight to twelve inches deep, you’ll need to remove them each time you prepare or cultivate the garden. They are also hard to clean if they become clogged.
There are two basic kinds of drip-ooze systems, and each is suited for different plants. What I call “discrete interval emitter,” or drip irrigation lines, have small metered outlets at regular spacing (usually every foot or foot and a half, though you can make up your own lines from scratch at any spacing you like). This kind works quite well for plants that are spaced fairly far apart from one another, like tomatoes or squash. Each plant has its own emitter and stays well watered, while the weeds and open ground in between them stay dry, which saves weeding as well as watering. On the other hand, ooze tubes work better for closely spaced crops, like carrots or spinach. An ooze tube is a porous-walled hose that uniformly oozes water over its entire surface. This moistens the whole area for a foot or two on each side of the hose (depending on soil type).
Purely as a practical matter, it makes sense to have some of each type, but the emitter types are usually made of virgin polyethylene or a related formula, while the ooze tube can be made from recycled auto tires. Since discarded tires are an enormous American landfill problem, and water shortages an increasingly frequent occurrence, using ooze tube irrigation is a satisfying way for a home gardener to solve two problems at once.
The equipment for overhead watering is much more diverse, most of the difference being at the end of the hose. Note that as with most of a gardener’s basic equipment, hoses are no place to skimp. Cheap, plastic hoses quickly become brittle and stiff, which makes moving them around the garden not only a hassle, but frequently a real danger to the plants. After a few seasons of Christmastime hints to my family, I now have plenty of reinforced rubber hose, ¾-inch in diameter, in a range of different lengths, so that I can use the minimum length for each job. Not only is this neater, but it preserves water pressure for the job at hand: running sprinklers. The performance of any kind of irrigation system is highly pressure-dependent, and there’s no sense losing pressure before the water even gets to the business end of the hose. For really large gardens, professional impact sprinkler heads are the way to go. There are some new Israeli-designed, plastic impeller types that perform better, but they are difficult to find. Either kind should be mounted on six-foot-tall supply pipes if you want to get even coverage. That way the water spray is above all but the tallest crops.
Oscillating wand type sprinklers can water square or rectangular spaces. But in my experience the coverage is not really even, and the motion of the spray head on wet ground makes a bit of a mess in open soil. Diffusion-type sprayers may make a lot of sense for small, rectangular, raised bed gardens. Diffusion sprayers don’t move, but instead direct a spray of water against a specially shaped part that causes the stream to splatter in a particular pattern. They, too, are sloppy, but both of these put water out faster than impact sprinklers.
Some people prefer to water by hand; for a small garden that may be all that’s necessary. But you should still choose your spray head with care. The trigger grip types are useful for washing (and for transplanting), but are too hard to control for irrigation. The same is true of nozzle types, but even more so. What you should get is a fan spray, which breaks the stream into a wide, relatively narrow band. This slows down the process enough so that the soil has time to soak up the water, and the shape makes it efficient, too. Dedicated hand-waterers like to put a gooseneck extension handle on the end of the hose leading to the spray head, not only to make holding it for extended periods more comfortable, but also so they can get the head down low and spray upward in an arching stream. By doing this they mimic the force of natural rainfall more closely.
One last piece of irrigation equipment we find useful is a siphon proportioner, a small device that screws into the hose line. By suction it pulls liquid fertilizer from a pail at a constant rate (depending on the water pressure and flow). It makes care of early spring seedlings much easier and allows convenient side dressing of crops later in the season as well. Whatever kind of fertilizer you use, even if not organic, this is an invaluable device for fertilizing seedlings. An anti-backflow device is built in to keep fertilizer or water from traveling back into the sill cock.
The amount of water your garden gets, whether from rain or irrigation, is vitally important to its success, and a small, inexpensive rain gauge is all you need to track this successfully; just empty it after each rain (or watering) and keep a running tally. After a few seasons you’ll have a good feeling for just how wet or dry your garden is.
Another small piece of equipment which will put you in closer touch with what is actually happening in your garden is a soil and compost thermometer. This is a small, weather-and-break-proof thermometer mounted on a spike that you can stick into the ground (or the compost pile). Soil temperature is critical to germination of seeds, and planting at the proper time removes the need for seed treatment, so for an organic gardener this is nearly an essential piece of equipment. The same thermometer can be used to monitor the temperature swings in your compost pile, which is an excellent gauge of its progress at turning garden refuse into nature’s best soil-conditioning fertilizer. As with the rain gauge, after a few years you will gain a practical insight into the actual progress of the seasons in your own garden.