Minnesota Pollution Control Agency

Editor's note: A rain garden photo suitable for use with this news release is available at www.pca.state.mn.us/newscenter/photos.html Saint Paul, Minn. -- Water quality experts have known for years that the use of rain gardens can have a positive effect on nearby lakes, rivers and streams. And a growing number of Minnesotans are discovering the benefits of these gardens designed to soak up rain water -- rain gardens can attract butterflies, bees and birds, too. A rain garden is a specially designed depression planted with flood-tolerant and water-loving perennial plants. Normally built curb-side, near a gutter downspout or in a flood-prone low spot, rain gardens soak up rain before runoff carries pollutants, such as lawn fertilizer and pet waste, to rivers and lakes. Rain gardens come in all shapes and sizes and usually reflect their owners' tastes. Some gardeners prefer shrub plantings, some like a well-groomed perennial flower garden, others are proud of their wild-looking Minnesota native plants. Building your rain garden
A rain garden should be about one-third the size of the area it drains, be at least 10 feet from the foundation of your house and well away from buried utilities. Also, keep the rain garden away from your septic system and a good 50 feet from your drinking-water well, if you have one. You'll want to locate your rain garden where water naturally collects. Some gardeners direct water from downspouts or driveways into their gardens. Test your soil to be sure it drains well. A simple, do-it-yourself percolation test (fill an 8-inch-diameter hole with water and see how fast it drains -- you can find instructions online) may indicate you need to replace or amend the soil with sandy soil that drains more efficiently. When dug, your rain garden's contour should resemble a gently sloping pond. Once you've put in plants, you can fill the garden with a generous helping of mulch. Deciding what to plant
As with any garden, two main factors should influence what you plant in your rain garden: light and moisture. A quick Web search will reveal hundreds of articles and books on planting a rain garden. But here are some quick tips:
-- Choose plants that can be submerged for up to 48 hours. But remember, because your rain garden is a depression, the plants at the bottom of the garden will be flooded longer.
-- Native Minnesota plants make good choices because they're adapted to our climate, are generally not invasive, and will provide food for wildlife.
-- Shrub and tree rain gardens are an attractive, low-maintenance option. -- Popular choices for well-drained soil (near the top of the rain garden) are the bright-orange butterflyweed (attracts monarch butterflies), the blue-flowered bottle gentian (bumblebees like it) and golden alexanders.
-- Good choices for soils that get some flooding (between the top and bottom of the garden) are little bluestem (the blue-green foliage turns bronze in the fall), blue false indigo, brown-eyed susan (provide food and habitat for birds and butterflies), and the black chokeberry (whose leaves turn deep-red in the fall).
-- Plants that thrive in soils with frequent flooding (the bottom of your garden) include marsh milkweed, the white-flowered turtlehead, "Isanti" red-osier dogwood (a shrub with red bark and white flowers) and many others. Handy resources
These links should get you started in the right direction:
-- Blue Thumb Program (Rice Creek Watershed District): www.bluethumb.org/raingardens
-- Minnesota Landscape Arboretum: www.arboretum.umn.edu
-- Metro Blooms: www.metroblooms.org
-- Duluth/Lake Superior Streams: http://duluthstreams.org
-- "Plants for Stormwater Design," available at www.pca.state.mn.us/publications/manuals/stormwaterplants.html.