Wednesday, June 25, 2014

How to Install a Drip Irrigation System

Drip irrigation is often the first choice for an edible garden. It provides slow and consistent water to the roots of each plant, where they need it the most, and prevents fungal diseases and weeds. It saves you water, because you measure the amount you use in gallons per hour rather than gallons per minute, and it practically eliminates water loss from overspray and evaporation. It’s also easier to install and more flexible than an inground sprinkler system and, once it’s in place, it requires less hands-on time during watering — a plus for those with larger gardens.


Before you rush out to get the parts, realize that it takes some time and a bit patience to install drip irrigation, though not as much as an inground system. Plan on a day for installation — or two, if you have a lot of ground to cover. Drip systems also require more upkeep throughout the growing season — emitters and water lines are easily dislodged, damaged and clogged. Fortunately, they’re also relatively easy to troubleshoot and repair.



Basic components. The components of a drip system can be found at most home improvement stores, online and in catalogs. Your basic system will include:


  • An antisiphon unit or a vacuum breaker that attaches to your water source, usually an outdoor faucet, but you can use an underground sprinkler antisiphon valve. Antisiphon units prevent water from entering your home’s plumbing system and are usually required by code.

  • filter or filters to prevent clogs that can plague the very small openings in a drip system. Choose between a larger Y- or T-filter for the entire system or smaller in-line filters.

  • pressure regulator to protect against too-high water pressure, which can cause drip lines to burst.

  • swivel adapter, also known as a thread-to-tubing compression adaptor, to tie the larger-diameter plumbing pipes into the smaller-diameter drip lines.

  • Drip tubing for the water lines to the garden, generally made of polyethylene. The ½-inch tubing is best for the main line and larger branch lines. (Note: There are two types of ½-inch tubing, which are not the same size and don’t take the same-color fittings.)

The ⅜-inch-inch tubing can be used for smaller branch lines, and ¼-inch microtubing can be used to encircle plants off these other lines.


  • Fittings to connect individual pieces of tubing. They can be straight coupling fittings, elbow joints, T-joints and four-way joints. You can also add shut-off valves. Green and blue fittings are for the two different types of ½-inch tubing; red fittings are for⅜-inch tubing.

  • Assembly tools, including punches, stakes, goof plugs and end caps or clamps.

  • Emitters, which deliver water from the lines to the soil. They generally dispense ½ gallon, 1 gallon or 2 gallons per hour (gph). Emitters with different rates of delivery can be used in a single system. The slower the drip rate, the more emitters you can add to the line and the greater distance your drip lines can run.

Note: When planning for emitters, take your soil type into account. Use 1-gph emitters, either at each plant or, for closely spaced runs, spaced 1 foot apart. For clay soil use ½-gph emitters and space them farther apart. For sandy soil use 2-gph (or higher) emitters spaced somewhat closer together. Microsprayers also work well in sandy soil if you know that the foliage will dry quickly.


Additional components. Other options you might want to consider:


  • fertilizer injector. It allows you to incorporate nutrients into the water line.

  • Emitter lines, similar to soaker hoses, with the emitters preinstalled; a ½-inch line is ideal for edible gardening.

  • Specialty emitters for specific plants or situations, including adaptable-flow emitters, pressure-compensating emitters (good for sloped or large gardens) and nonplugging emitters.

  • Sprayers and sprinklers that can deliver a slow stream of water in a variety of patterns, including a gentle mist. They’re not commonly used for edibles but can be a good choice for salad crops.

  • battery-powered timer to automate the system.

  • caddy or container to hold all the pieces, both for installation and later repairs.


Before You Buy


If your edible garden is relatively compact and level, your watering needs are fairly uniform and your water pressure isn’t too high, a prepackaged drip irrigation kit designed for vegetable gardens will probably have everything you need, including step-by-step instructions. It’s a good way to get started.


If things are a bit more complicated, you’ll need to do some preplanning before you head to the store. Don’t despair. It seems like a lot to do, but simply consider these guidelines for making the most of your system. It is possible to skip a step or two and chances are, things will be fine.


Again, the beauty of drip irrigation is that if what you put in doesn’t work, changing it is much easier than redoing an inground irrigation system.



Start with the garden’s design. There is always the familiar rectangle or square patch of ground, either small or large, with neat and tidy rows of plants, but before you commit to that, consider other options.


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How to Install a Drip Irrigation System

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