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“Off-the-shelf” drip irrigation kits usually supply everything needed to get started. Clockwise from top: black drip tubing, water filter, pressure reducer, assorted fittings and brown dripline. Punch-in drip emitters and factory-installed emitters are equally effective.
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A water filter and pressure reducer are necessary components of a drip system. Most can be attached directly to an exterior hose bib.
Watering plants is a science and an art. The goal is to get the just-right amount of moisture to the roots, and only the roots, to promote healthy growth. Hand watering is always an option for small gardens, but for larger plots, most gardeners rely on sprinkler systems.
Unfortunately, sprinklers are a terribly inefficient method of irrigation. On a sunny day, up to 50 percent of the water sprayed into the air evaporates before it hits the ground. Sprinklers apply water indiscriminately, providing moisture to both garden plants and weeds alike. They also wet foliage, leaving plants at risk of disease.
Drip irrigation systems, which apply water directly to the soil at a plant’s root zone, are a better alternative. They are up to 95 percent efficient, and by keeping foliage dry, they can reduce or even eliminate the need for fungicides.
Simple drip irrigation systems are easy to install in your home garden. There are “off the shelf” kits available, or you can build your own using the parts available at most lawn and garden stores.
For precise irrigation control, gardeners can use solid drip tubing and manually install external, punch-in emitters to deliver water to specific plants. Emitters are commonly sold in 1/2-, 1- and 2-gallon over hour (gph) flow rates, allowing you to regulate water flow as needed.
The easiest way to start with drip irrigation is to use dripline—flexible polyethylene tubing with pre-installed drip emitters spaced at regular intervals. Dripline systems create a uniformly moist soil area in the planting bed and are well-suited to both landscape applications and vegetable plots.
In either case, drip emitters have small pores that cannot tolerate standard household water pressures and are easily clogged. Look for connection hardware that includes a 30-psi pressure reducer and a 150 mesh filter. Most of the commonly available drip irrigation kits come with these two necessary components.
When placing dripline in vegetable gardens, run the tubing along the crop stems to create a wet strip of soil that supplies water to the crop’s roots, but not to the middle of the row, where weeds often proliferate. In a flower or shrub border, install the dripline in a grid pattern, woven among the plants. In both instances, place the dripline above the soil and mulch over it. This maximizes efficiency, minimizes clogging and gives your garden a tidy appearance.
For easy math, I recommend using dripline that has 1 gph drip emitters spaced at 18 inch intervals along the tubing. Space the individual driplines 2 feet apart, and you will have a system that applies a little more than the equivalent of 1 inch of water in 2 hours. Of course, you must also consider your soil type when determining how often your system should run, as sandy soils require irrigation more frequently than clay soils.
As South Carolina’s population continues to grow, there will be increasing demand on our limited water resources. Precise irrigation methods will enable us to keep our plants vigorous and healthy while reducing stress on our water supply. For more details on drip irrigation, visit Clemson Extension’s Home & Garden Information Center.
S. Cory Tanner is an area horticulture agent for Clemson Extension based in Greenville County. His responsibilities include coordinating the Greenville County Master Gardener program and providing home gardening advice. Contact Tanner at shannt@clemson.edu .