GARDENING IN GWINNETT: Rain gardens protect landscape from polluted runoff

Stormwater is often polluted with fertilizers, chemicals and debris. Positioned under downspouts, shallow depressions in the lawn or driveway intercept stormwater that ordinarily flows off roofs into the street but instead seeps into the ground. This water is captured by a garden with plants and slowly filters into the ground rather than going into the storm sewer.

Specialized rain gardens are a nice way to reduce such polluted runoff. A rain garden helps in other ways, as well: it can prevent stream bank erosion and reduce the risk of localized flooding.

The best place in the yard to plant a rain garden is in a natural low area, at least ten feet away from the building. Make sure you understand what kind of soils you are working with, since soils can have differing levels of fertility, drainage and pH.

Start your rain garden by setting borders, either by spray painting the boundaries or laying down a rope. Mix 2 to 4 inches of topsoil, peat moss or compost in the soil. Plant a ground cover, like liriope, around the border of the garden to reduce the velocity of the stormwater runoff flowing into the garden.

Be sure to install plants that are hardy and can survive the conditions of the rain garden. Trees like willows, red maples and river birch are excellent choices. Shrubs, such as the Virginia sweetspire and beautyberry, as well as perennials, like swamp sunflower and blackeyed Susan, also work well. After planting, apply 3 inches of a mulch with larger particles so it does not float away.

Note that Gwinnett County has a stormwater utility fee to fund stormwater activities such as replacing stormwater pipes, fulfilling regulatory requirements and reducing pollution. Residents can often obtain a discount on stormwater utility fee credits in exchange for participating in community stormwater activities or for implementing practices that can reduce the impacts of stormwater in the community.

Rain gardens are among several ways to do this. Residents who build rain gardens on their property can receive up to a 10 percent credit. To do so, submit an application with a site plan showing the size and location of the rain garden. For more details, go to www.gwinnettstormwater.com and click on stormwater utility.

Timothy Daly, MS, is an Agricultural and Natural resource Extension Agent with Gwinnett County Extension. He can be contacted at 678-377-4010 or timothy.daly@gwinnettcounty.com.