Plant a Rain Garden for Next Spring to Reduce Urban Erosion

First posted on 09-24-2010

Erosion and sediment pollution due to storm runoff are growing problems in most urban areas. Excessive storm runoff results in loss of topsoil, nutrients and water as well as sediment buildup in nearby lakes and streams.

“Homeowners and landowners looking ahead to plan spring landscaping can take some simple, inexpensive steps to slow storm runoff,” said Allen Thompson, University of Missouri biological engineering professor.

One way is to construct rain gardens at a low spot on your property.

Rain gardens are shallow depressions planted with native perennial wildflowers and grasses. They are designed to contain, filter and absorb stormwater runoff, Thompson said.

Pick a suitable area for your rain garden. Dig out a depression in the center and transfer soil to edges to form a berm. Add gravel or mulch to control weeds and then install the plantings. Connect your rain garden with a 4-inch corrugated pipe connected to a downspout to direct rainwater to your new rain garden.

“This is a good method for channeling runoff from your roof. You have constructed a small wetland that helps reduce drainage and flooding problems. It helps to keep pollutants out of the stormwater system and provides a place for flowers and wildlife,” he said.

Native perennial plants work best because they are adapted to the local climate and are able to withstand flood and drought. They are easy to maintain and do not need fertilizer.

You can install rain gardens at various locations on your land that receive full sun and are at least 10 feet away from your house.

There are two types of rain gardens. Dry rain gardens are installed in pre-existing or newly created depressions that are 2-6 inches deep. Wet rain gardens, placed in locations that receive a regular supply of water runoff, require a deeper depression-up to 18 inches.

Shrubs and grasses are well-suited for side slopes. Buttonbush, giant hyssop and fringed brome are wet species for lower portions of the rain garden. Occasional weeding may be needed but can be minimized by incorporating surface mulch. Initial hand watering can improve plant survival until plants are well-established.

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