By David Wann
Water costs are steadily rising, as is the price of food. A drip-irrigation system can help ease both of these things. With this type of irrigation, less water is needed and yields are usually higher, because water is applied directly to the root zone.
Drip irrigation also reduces weed growth, as compared with a sprinkler, as well as diseases like mildew and fire blight that are related to dampness on leaves. And you spend less time hand-watering and moving sprinklers around, and more time harvesting and eating fresh produce.
Installing a drip-irrigation system may seem daunting—you can easily imagine a tabletop of strange-looking connectors, a spider web of buried plastic tubing just waiting to be punctured by your garden spade, and the need for tools that only plumbers and engineers use.
But I have good news: It’s not really much more complicated than buying, wrapping and mailing a gift. You measure, you cut, you fit, and before you know it, your task is done.
Last year I installed a “T-Tape” drip system for my vegetable garden, and an emitter-tubing system for my fruit trees. I plan to fine-tune both systems this season by adding timers and zone-specific shutoff valves. I gleaned a few tips that may help you install and maintain your own system.
First, I did online research about T-Tape—a fairly low-cost, durable product for irrigating raised beds and long rows in a garden. A few gardening friends had recommended it for its ease of installation, good performance and relatively low maintenance.
A T-Tape system has three main components: a garden hose, mainline tubing and T-Tape. Water flows from the faucet through the garden hose to the mainline tubing, which is really just a tube similar to a hose and the “supply line” that delivers water to the T-Tape. The T-Tape is just a flat plastic hose that inflates and drips as water flows through it. In homes with high water pressure, a pressure regulator and mesh filter can help slow the flow from the hose to the mainline, enabling the water to “drip” through the drip holes, called emitters, on the T-Tape. The manufacturer precuts emitters into the tape, which is the final leg of the drip-irrigation system that delivers the water to your plants.
Drip-irrigation systems also have several other smaller components: fittings like elbows, tees and crosses that direct the flow where you want it to go; couplers
to repair mainline tubing if it gets cut by mistake; hold-down stakes to keep the main-
line tubing in place; and “Easy Loc” fittings to connect the T-Tape to the mainline.
When using T-Tape for vegetable crops, tape with emitters spaced 8 inches apart works best, because as water drips from the emitters it spreads out underground up to 2 feet in diameter, depending on soil conditions and the amount of time it drips.
One-hundred feet of high-flow T-Tape provides about 40 gallons per hour, and the volume of water that drips from an emitter at the end of a T-Tape line is just as strong as at the beginning of the tape’s connection with the mainline tubing.
I bought a 750-foot spool of T-Tape for $90, and a 500-foot roll of mainline tubing for $65. The various other parts I needed cost another $100: an inline pressure regulator and filter at the beginning of the system; elbows, couplers and tee fittings; hold-down stakes, end caps and crimping devices.
For a modest investment, I got a system that will keep crops happy, even in extended droughts. Both the mainline tubing and T-Tape are designed to last up to seven years if protected from the sun, so I shallowly buried (and marked) the mainline tubing, and I roll up the T-Tape at the end of a season, making sure to label which line goes where in the garden.
After making a few diagrams of how I would lay out my drip system, I calculated and ordered the tubing and T-Tape I’d need. I used a standard garden hose from the faucet to the mainline tubing, or supply line, since there are standard couplers to connect hoses and tubing. It’s important to think about how much water each crop will need and group your crops accordingly. I designed my system so that the water supply to less-thirsty crops, like basil, arugula and garlic, can be temporarily shut off while I irrigate crops that require more water.
Although T-Tape can be buried, one of its strengths for garden use is that it can be laid above ground, where you can spot possible leaks and also avoid slicing it. I use leaves, grass clippings, wood chips or burlap bags to mulch the lines and hold in moisture, and thriving row crops quickly hide both the mulch and lines. But you’ll still know where the lines are, because they’re always just beneath your rows.
You can calculate the exact amount of water supplied by multiplying the manufacturer’s rated gallons per hour for your emitters by the length of time the system is on. My own methods are a bit more intuitive: I watch the vigor of the plants and the moisture in my loamy soil to determine when and how long to turn on the drip irrigation.
Some drip-irrigation suppliers provide free design consultation—a real plus for people like myself who are challenged when it comes to details. Drip-irrigation installation and maintenance literature, and instructional online videos like those at dripworksusa.com (type “videos” into the search bar), emphasize a few key points when creating a drip system:
- Start small and add on as you become more familiar with the system.
- Keep plenty of Goof Plugs and couplers on hand to cover mistakes.
- Don’t over-tighten connections; finger tight is usually adequate.
- When you’re ready to install mainline tubing, roll it out and stake it down to avoid kinking.
- Let the mainline tubing and T-Tape sit in the sun a while before installing, to make them more pliable.
- Use a pressure regulator and filters at the beginning of your system to avoid blowing out connections and plugging the emitters.
- Use a timer to provide convenient, dependable irrigation while you’re away.
Once your drip system is in the ground, your water bills will drop, your crops will thrive and you won’t fret as much during droughts, because your plants will be precisely watered at the root zone.
Have a great growing season!
David Wann runs a community garden in Golden, Colo. He is author and coauthor of 10 books on sustainable living and design. His most recent book is The New Normal: An Agenda for Responsible Living. Find out more online at davewann.com.