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Originally published Thursday, June 28, 2012 at 9:00 PM

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Collecting rainwater for a garden

The Gardener Within: Joe Lamp'l, a master gardener and author, shares how to set up a rain-collection system. The setup can be as simple as a rain gutter, downspout and barrel.

Scripps Howard News Service

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We've discussed collecting and storing rainwater before, but let's revisit the various aspects involved for the benefit of those interested in getting started in the practice.

The setup can be as simple as a rain gutter, downspout and barrel. Kits are available from catalogs and the Internet, but you can easily make your own. Before getting started, however, check local building codes to be sure that it's OK to have rain-collection systems in your area.

First, to keep any debris from the roof from getting into your system, install a wire-mesh or plastic screen over the opening in the gutter where it is connected to the vertical downspout. Next, choose some kind of barrel or tank to collect the water. Many home-improvement stores and garden centers sell 55- to 75-gallon plastic barrels for around $50 to $100. Complete kits, including, leaf screens and downspout connectors, go for $100 to $250. If you use a recycled barrel, select one that's been used for food storage rather than any kind of chemical.

Barrels MUST have a sturdy cover that can hold the weight of a child who might climb onto it. Screens over all openings will keep out mosquitoes and small animals. During winter months, drain the barrels in areas that experience freezing weather.

If you're making your own system, install a heavy-duty plastic drain spigot into the barrel wall using waterproof plastic cement. Select one with common-size threads that can attach to an ordinary garden hose, and locate it as low as possible on the side of the barrel. Place the barrel on a raised platform to make room under the spigot for a watering can or hose attachment, and you're ready to water.

A typical 1,000-square-foot roof can provide about 500 gallons of water from only 1 inch of rainfall. When the barrels are full, divert the rest of the water away from the house or, better yet, into a rain garden.

A rain garden is just a deep depression that collects runoff from impervious surfaces like roofs and driveways and lets it soak slowly into the ground. They're planted with shrubs and perennials and maintained like any other landscaped area of a yard.

Install a rain garden 10 feet from the foundation, about 30 feet from the downspout. Keep it away from low areas that always seem wet; they probably don't have the loamy or sandy soil that will percolate water properly. To test, dig a 6-inch hole and fill it with water. If the water is still standing 24 hours later, choose another spot. Avoid septic systems and wells, too. They could become contaminated from the collected water.

A typical rain garden needs about 75 square feet of collecting area, so plan on a 10- by 8-foot, flat-bottomed bowl 6 inches deep. The bottom should be fairly level, and the sides gently sloped. Use the dug-out soil to make a retaining berm on the downhill side of a sloped area.

Use plants that do well in wet soil, but can also tolerate very dry conditions. Try perennial iris, black-eyed Susan, cardinal flower, astilbe and spiked gay feather, along with grasses like panicum, carex or sedge. Mulch with a layer of bark or gravel to keep down weeds and stabilize the soil.

Joe Lamp'l, host of "Growing a Greener World" on PBS, is a master gardener and author. For more information, visit www.joegardener.com.

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