Make yourself a rain garden
Summer time is thunderstorm time across the country. All that water rushing off roofs, driveways and walkways is loaded with oil and other pollutants, and it all ends up in our sewer systems. Since municipal storm water treatment plants often can’t handle the deluge, the untreated water dumps into our natural waterways. The EPA estimates that as much as 70 percent of the pollution in our streams, rivers and lakes is carried there by storm water.
We can help stem the flow of polluted storm water into our streams by planting a garden, a rain garden. Rain gardens are specially constructed to collect storm water instead of letting it run off your property. These gardens are shallow depressions located at low points in your lawn that are planted with native plants and wildflowers, so they’re both functional and attractive. Storm water is funneled naturally to the garden, where it’s stored and allowed to slowly absorb back into the soil.
Building a rain garden
Your rain garden should be located at least 10 feet from your home in a low spot where water naturally collects. It should have at least one-half day of sun and a gentle slope leading from your roof downspout, driveway or walkway to the garden. You can create a low swale from the roof downspout to the rain garden to ensure that water drains into the garden.
To build the rain garden, mark out a 150- to 450-square-foot area, depending on the size of your house and amount of paved areas. Remove the sod and dig a shallow depression about 6 inches deep. Use the soil to form a berm on the lowest side of the garden to retain water. A 6-inch-deep rain garden should drain water within 7 hours. If the rain garden is deeper, the water may stay longer, creating a mosquito-breeding site.
Rain Garden Plants
Select regionally adapted plants that can withstand periodic flooding and offer seasonal color and interest. When fully planted, your rain garden will look like any other flower garden in your yard. Plant in clumps of at least three of each particular plant, and include ornamental grasses and sedges for texture and to help prevent soil erosion. Create a special ‘rain garden’ soil mix of 50 to 60 percent sand, 20 to 30 percent topsoil and 20 to 30 percent compost. Dig this mixture into the soil to depth of 2 feet before planting.
The native plants you grow will depend on where you live. Some examples are swamp milkweed (Asclepias incarnata), queen of the prairie (Filipendula rubra), marsh marigold (Caltha leptosepala), columbine (Aquilegia formosa), maidenhair fern (Adiantum pedatum), Joe-Pye weed (Eupatorium maculatum) and turtlehead (Chelone lyonii).
After planting, keep the plants moist, well-weeded and mulched with shredded hardwood bark. (Bark chips and nuggets will float away during heavy rains.) Your rain garden will not only help reduce water pollution, it will also be an inviting place for butterflies, bees and birds to visit too.
Charlie Nardozzi, a nationally recognized garden writer, book author, speaker and radio and television personality, has appeared on HGTV, PBS and Discovery Channel television networks. He is the senior horticulturist and spokesperson for the National Gardening Association (www.garden.org) and Chief Gardening Officer for the Hilton Garden Inn.