While they can take some work to put in, the benefit of having a rain garden in a landscape that has drainage issues can be well worth the time it takes to install.
A rain garden is a depressed (low lying) area in your landscape that allows water runoff to collect and slowly absorb into the ground instead of letting water move freely over topsoil, eroding soil into streams. A rain garden often uses native plants because many can handle drought conditions as well as periods of high moisture. A rain garden will prevent soil and other material from polluting streams by as much as 30%.
Runoff includes any water that moves quickly from rooftops, sidewalks, roads, parking areas, and from higher elevations to lower elevations during flooding. Any area that is impervious and does not allow water absorption into the soil profile is a candidate for a rain garden site.
The easiest of all rain gardens is one that is installed in an already low lying area that continually accumulates water during periods of intense rain. In this situation the depression can be filled in with either mulch or with larger rocks and pockets of soil prepared for native plants. When rainwater fills the depression the addition rock and plants will slow the movement of the water over the ground, giving it time to be absorbed by the roots of native plants and to infiltrate the ground through the mulch. It is important to familiarize yourself with the subsoil in areas where a rain garden might work to assure that clay pans will not prevent water from penetrating into the ground.
Rain gardens are not intended to be permanent water pools but simply a way to slow water that moves over the surface just long enough to soak into the ground. Because the water is not prohibited from entering the soil, the water will drain within 2 or 3 days, preventing a buildup of mosquitoes. One caution is to keep your depression further than 10 feet from your house to prevent any damage to the home from excess water. With that requirement in mind don't place a rain garden under your drain spout right next to your house.
Plants that are often used in a rain garden include sedges, grasses, asters, indigo, penstemon, black-eyed susan, goldenrod, iris, blazing star, cardinal flower, lobelia, phlox and loosestrife. You can include any planting mix that you prefer as long as they are adapted to both drought conditions and periods of high rain.
Some of the benefits of using a rain garden include providing a use for problem areas in the yard, improving water quality, attracting birds and butterflies, ease of maintenance, and providing food and shelter for smaller wildlife. Now is a great time to install a rain garden to be ready for the spring season. Give it a try; you might be surprised by your success.
Helpful Sources: Rain Gardens -- A how-to manual for homeowners. Copyright 2003. University of Wisconsin Extension. Publ GWQ037. Wisconsin DNR PUB-WT-776-2003 http://www.dnr.state.wi.us/org/water/wm/dsfm/shore/documents/rgmanual.pdf
The Extension office is open Monday - Friday, located in Kennett, Missouri at 233 North Main Street. For horticulture questions contact the horticulture specialist at 573-686-8064. MU is an equal opportunity/ADA institution.