Thinking about changing your garden from a traditional sprinkler system to drip? Dazed and confused in the irrigation aisle at the garden center? No budget for an irrigation contractor? Fear not, drip irrigation is easier than it looks!
First, draw a plan of your yard. Use one corner of the lot or the house as your “control point,” measure the distance to all features from this point and transfer the measurements to paper, using ¼ inch to represent 1 foot in the field. Locate big things first: the house, other structures, trees, shrubs, driveway, and walkways. Then locate the exterior faucets and the water supply to any existing irrigation system. Measure and draw existing and planned flower and vegetable beds and turf areas. When complete, make a couple copies of the drawing for planning purposes.
Next, group plants with similar water requirements into single zones and consider how often each plant grouping/zone needs water. Turf should be irrigated with traditional sprinklers on its own zone(s) – avoid mixing drip lines and sprinklers in one zone. Shrubs and trees need deep watering infrequently. In general, shady areas need water less often than those in full sun. Vegetables have higher water needs than flowers. Tomatoes are finicky so you may want to water those by hand. New plantings, even xeric, will need more water until established.
If you have a traditional sprinkler irrigation system, you can convert whole zones to drip. Most sprinklers are connected to water supply piping with a ½-inch threaded nipple. Simply remove the sprinkler and replace it with an adapter purchased from your local home center. From this adapter, run the larger, usually ½-inch, plastic piping along one side or in the middle of the zone; this line can be mulched over after the installation is complete. Note: there are several brands of drip irrigation equipment and, in general, their piping and parts are not interchangeable. Select a brand that is available near you and stick with it. “Professional grade” materials seem to last longer.
There are three basic types of “drip” devices: drip emitters, micro-sprinklers, and misters. Your plants’ watering needs will determine the type of drip device you install. Drip emitters include soaker hoses, tubing with emitters embedded every 6 - 12 inches, laser-drilled tubing, adjustable emitters on stakes, and single drippers rated at various flows. Micro-sprinklers are usually mounted on stakes with varying areas of coverage and flow rates. Misters are used to humidify an area or to start seeds, but are not great for watering mature plants. These devices connect directly to the larger supply line, or at the end of ¼-inch plastic tubing, routed to the base of plants.
Many drip systems use micro-sprinklers positioned at regular intervals; however, emitters and soaker lines do not wet the plant leaves and spread disease, or use precious water on areas with no plant roots, thereby encouraging weeds. Simply place an emitter or two at each plant or shrub, or snake a soaker hose throughout your perennial bed. Remember that drip irrigation is very flexible and adjustable and parts can and should be changed as your landscape matures. You may start greens from seed with a micro-sprinkler, but as they emerge and become little plants, you then switch to an emitter line, reducing the chance of powdery mildew and leaf burn.
Other essential drip irrigation parts include various fittings that connect drip lines to supply lines or drip emitters/sprayers to drip lines. There are good manufacturers’ installation guides at home centers or online, and most centers have knowledgeable staff available to answer questions.
Drip irrigation uses less water at lower pressures than traditional turf sprinkler systems. Key to the success of your drip system is an adjustable pressure reducing valve and pressure gauge on the system water supply that adjusts the outlet (system) pressure to 25-35 psi. Additionally, plumbing code requires a backflow prevention device be installed. These two devices should be located on the irrigation supply line, downstream from where it connects to the house water system.
With a little planning, patience and do-it-yourself skills, you too can enjoy the benefits of drip irrigation in your garden.
Note: This article applies only to mountain gardeners with outdoor water rights.