Flexible parts snap together
Think of a drip irrigation system as an upscale soaker hose. But instead of water spraying out every 2 inches, it can seep out every foot—or maybe every 3 feet—drip by drip. With a little planning, those drips can line up with the root zones of plants.
Drip-irrigation parts snap together like modular toys and can be adjusted as your garden changes. You’ll need a filter, water-pressure reducer, hose swivels, emitters, and 1/2- or 5/8-inch flexible polyethylene tubing—also called the submain. You may need a backflow preventer if it’s required by your municipal water department. Optional parts include 1/4-inch solid tubing, 1/4-inch drip line, connecting tees, 90-degree elbows, connecting barbs, hold-downs to keep tubing in place, goof plugs to fill holes you decide not to use, timers, and fertilizer injectors. You can buy these parts at some hardware stores or garden centers, or from companies specializing in irrigation systems. Parts from different manufacturers are almost always interchangeable.
System costs are very reasonable. You could cover about 250 square feet with drip irrigation for $20 to $50 in parts, not including a timer. For installation, all you need are strong shears to cut the tubing, and a 16-penny nail or commercial punch to poke holes in the submain for the emitters and 1/4-inch tubing. You can bury the submain just below the soil, or leave it on the surface and cover it with mulch. Either way, I try to run it along the edge of a bed so I won’t accidentally disturb it. The 1/4-inch tubing can also be buried, but leave drip lines on the surface so the emitters don’t clog with soil. I use a combination of buried and mulched lines in my garden, so only small emitters are visible here and there.
You can convert an existing sprinkler system to drip irrigation by plugging all the spray heads on a circuit but one, and running a drip circuit from that one head. Remember to choose circuits that aren’t needed to water the lawn.
There are two critical points to keep in mind. First, drip irrigation works on low pressure—from 10 to 30 pounds per square inch (psi). However, water pressure at hose spigots runs anywhere from 50 to 100 psi so you need a pressure reducer on every drip-irrigation circuit. Second, as a conservative rule of thumb, any one drip-irrigation circuit can only handle about 225 gallons per hour, so you’ll need to calculate the total gph for all emitters on each drip circuit to make sure they don’t exceed this amount. Each emitter has its own rating, so simply add up the numbers.