A lot of rain falls on impervious surfaces that can’t soak up water. Instead of allowing all of this water to uselessly drain away, home gardeners can create an aesthetically pleasing area that will allow the water to drain back into the ground, away from the house. This is the idea behind a rain garden.
As the name implies, a rain garden collects and absorbs rainwater, preventing it from running off a property. Runoff mainly comes from roofs, driveways and lawns. A properly placed rain garden allows about 30 percent more water to soak into the ground than a conventional lawn.
A rain garden will intercept pollutants such as fertilizers, automobile fluids and pet waste from entering into storm drains and retention ponds. Some studies show that about half of the pollution that stormwater carries comes from home yards.
Why should a home gardener consider installing a rain garden? Besides being an attractive addition to a yard, a rain garden provides environmental benefits. A rain garden can be a home gardener’s personal contribution to reducing the amount of pollutants washing off to lakes and streams. A properly placed rain garden will increase the amount of water filtering into the ground. Native plants used in rain gardens provide habitat for birds, butterflies and beneficial insects.
A rain garden is natural landscaping, generally a combination of native wildflowers and grasses which replace areas of a lawn. Native plants are a great choice for rain gardens as they are deep-rooted and tolerate both wet and dry spells.
Rain gardens are placed in a full-sun to part-shade location to collect water
from downspouts or sump pumps. The garden should be placed a minimum of 10 feet
from a foundation in a low spot where water naturally drains.
A rain garden is bowl-shaped, allowing water to flow into it. The middle of a rain garden will hold water during heavy rains, so the water will gradually soak into the ground. After most storms, standing water should only last a few hours.
A rain garden will need some weeding and watering during the establishment period, which is the first two years. After the plants are established, little care is needed, except occasional weeding and thinning of plants.
Sizes and designs of rain gardens vary, based on the yard size and layout. University of Wisconsin Extension offers several publication on home and garden clean water practices including, Rain Gardens: A how-to manual for homeowners, http://clean-water.uwex.edu/pubs/home.htm#rain. This publication includes information about layout, design ideas and plant lists, and how to build a rain garden.