Photo by Alexander Shapovalov - Getty Images
Rain Garden
Rain Garden
As we learn more about contaminants such as fertilizers, oils and pesticides that travel into our drinking water via rainwater runoff, more homeowners are seeing rain gardens as a practical and aesthetically pleasing option to curb this pollution to our water supply.
Rain gardens are shallow depressions consisting of native perennials, shrubs and flowers. The root systems hold and absorb rainwater runoff from roofs, lawns, driveways and parking lots. The rainwater hydrates the plants, which in turn infiltrate water into the ground along root pathways.
The native plantings in rain gardens also attract birds, and native pollinators such as bees and butterflies.
Rain gardens can also be an effective way to keep water away from houses, which can help prevent basement and foundation damage.
According to the Wisconsin Department of Natural Resources, rain garden plants capture 30% more water than a regular lawn and filter that water into the ground instead of the water supply.
Milwaukee Metropolitan Sewerage District’s (MMSD) 2025 Rain Garden Plant Sale, in which community members can pre-order native plants at a discount to install their own rain gardens, sold out well before the upcoming June 7 pickup—a testament that interest in rain gardens is growing.
Installing a Rain Garden
The best time to plant rain gardens in is spring or early fall. The MMSD recommends choosing a location that’s six to 10 feet away from your house, and at least five feet from a septic tank and eight feet from a well. Don’t install a rain garden in an area where water ponds. The Wisconsin DNR suggests placing a rain garden within thirty feet from the mouth of the downspout. An ideal location is on a gentle slope that catches downspout water.
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For more details on planning a location and terracing a rain garden, visit dnr.wisconsin.gov/sites/default/files/topic/Stormwater/RainGardenManualPrint.pdf and mmsd.com/what-we-do/green-infrastructure/rain-gardens.
When choosing plants for a rain garden, look for deep-rooted native perennials that will infiltrate water. Certain plants attract butterflies while others attract birds. Butterflies are attracted to milkweed, woodland phlox, bergamot, black-eyed Susan, New England aster, wood violets, and sky-blue aster.
Plants which birds are attracted to include wild senna, sunflower varieties, black-eyed Susan, wild petunia and little bluestem.
For shady areas, consider jack in the pulpit, bellflower, various sedges, shooting star, white trout lily or great blue lobelia. The University of Wisconsin Extension recommends plants that have a well-established root system; use only nursery-propagated plants. Do not collect plants from the wild.
Hand-weed the rain garden during the first two years. Once the rain garden is well established, native grasses will mature and overtake any weeds. Over winter, leave stems and seed heads for wildlife cover and bird food.
Be sure to monitor the water level in the rain garden so there’s no standing water for more than a day. If young plants are mostly submerged, dig a small opening in the berm to let out some of the water. As your plants mature, standing water should diminish and the plants’ infiltration rates will improve. To learn more, visit fyi.extension.wisc.edu/sewraingardens.
