Lesson 6: Special Features in Your Landscape
Rain Gardens
Homeowners across the country are discovering the joys and satisfaction of rain gardens. A rain garden is a landscaped area that actually replaces an area of lawn. Compared to a “normal” patch of lawn, a rain garden allows 30% more water to soak into the ground. Rain gardens are a good and inexpensive way to prevent the problem of urban stormwater runoff.
A rain garden is planted in wildflowers or other native vegetation. As the name implies, rain gardens are designed to soak up rainwater, mainly from the roofs of buildings, parking lots and hard surfaces. A rain garden is designed so that it fills up with a few inches of water after a storm. That water can then slowly filter into the ground, rather than rapidly running off into a storm drain, river or lake.
So, why are rain gardens important? The use of rain gardens can:
Help protect streams and lakes from pollutants that are carried by urban stormwater. These are pollutants such as lawn fertilizers and pesticides, oil and other automotive fluids and harmful substances that wash off roofs and paved areas. If you think about all of the oil slicks you see in a typical department store parking lot, you get an idea of the large quanity of chemicals that can end up in nearby lakes, rivers and streams. Rain gardens prevent this from happening.
Help to increase the amount of water that filters into the ground.
Enhance the beauty of yards in both residential and commercial areas.
Create habitat for birds and butterflies. Generally native plants are used in rain gardens. These native plants are great attractors for colorful butterflies and small birds.
Help protect communities from flooding and drainage problems.
A typical home rain garden can be in one of two places: 1) near the house to catch roof run-off; or 2) further out on the lawn to collect water from the lawn, roof, and other hard surface areas. Don’t put a rain garden: Within ten feet of the house so that water cannot seep into the foundation. Do not put a rain garden where water already ponds the goal of a rain garden is to encourage infiltration and wet areas are where infiltration is already slow. And do not put a rain garden directly over a septic system. In addition, rain gardens will thrive better in areas where they will receive full or partial sun.
Rain gardens can combine shrubs, grasses and flowering perennials. The garden itself is actually a depressed area, which is usually about six to eight inches deep. Rain that flows into the garden is retained in the garden for a short time after a rainstorm. The water slowly infiltrates into the ground or evaporates. The plants in the garden filter the water by trapping pollutants.
Remember that rain gardens are not ponds. Rainwater soaks into the garden, which is then dry between rainfalls.
Rain gardens are not breeding grounds for mosquitoes. Mosquitoes need 7 to 12 days to lay and hatch eggs. The standing water in a rain garden will last for only a few hours.
Once established rain gardens require little maintenance. Some weeding and watering may be required until plants get established.
For a sample diagram of a rain garden download the following pdf file Rain Garden
An excellent resource for learning more about rain gardens is the following website:
http://clean-water.uwex.edu/pubs/raingarden/
Another good resource is Gardens for a Rainy Day in the Minnesota Conservation Volunteer. Check our bibliography for more information on this reference.
