B. Rosie Lerner
Purdue Extension


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Rain Gardens Go with the Flow

Rain gardens are areas of the landscape designed to catch rainwater long enough to allow it to percolate slowly back into the groundwater rather than run off the soil. Rain gardens help recharge groundwater, improve the water quality of streams and rivers, reduce flooding, and provide cover for wildlife and butterflies.

Rain gardens can be just shallow depressions of a few inches or elaborately constructed sites, depending on available space and needs of the site. The garden's topography should be designed to encourage water flow into the garden. The site must drain well enough to allow slow and steady percolation into the groundwater. Soil drainage can be greatly enhanced by additions of finished compost in preparing the area.

Ideally, the rain garden should be located away from (10-foot minimum) and a bit below the grade of structures, such as the house, toolshed and garage. Rain barrels can be used to collect runoff water from house drainpipes and redirect to the rain garden. Reasonably level land will be much easier to work with.

Avoid placing the rain garden over a septic drain field or tank; a buffer of at least 50 feet is recommended. Be aware of shallow utilities in the area, and always call to locate and mark these utilities before you dig. Also avoid the edges of steep slopes where erosion is a risk.

As you consider the overall landscape design and appearance, like other gardens, you'll need to consider the mature size, growth habit, flowering, fruiting and other characteristics of your plant selections. Most rain gardens feature moisture-tolerant perennial flowers, native wetland or wet prairie wildflowers, and grasses, but shrubs and trees can be used in larger gardens. Keep in mind that plants will also need to be tolerant of periodic dry spells as well as heavy rains.

The following are a few species to consider for your rain garden planting, but it's by no means an exhaustive list.

Big Bluestem
Little Bluestem
Various Sedges

Black-Eyed Susan
False Indigo
Flag Iris
Great Blue Lobelia
Joe Pye Weed
Swamp Milkweed

American Beautyberry
Arrowwood Viburnum
Bottlebrush Buckeye
Oakleaf Hydrangea
Summersweet Clethra

Bald Cypress
Red Maple
River Birch

Additional information on rain gardens can be found online at:

Purdue University

University of Wisconsin

Marion County Soil and Water Conservation District

The Ohio State University Extension

University of Kentucky Extension


Writer: B. Rosie Lerner
Editor: Olivia Maddox