In the Garden:
Planted by local Master Gardeners, this rain garden filters runoff from a public parking lot and serves as a community demonstration garden.
Meet the Eco-Friendly Rain Garden
Rain gardens are a simple and effective way to minimize both water pollution and storm water damage. Never heard of this type of landscape feature?
A rain garden is simply a low area that is planted with a variety of shrubs and perennials that are tolerant of both wet and dry conditions. The design of a rain garden can be formal or informal, to suit the gardener's taste, and if it incorporates native plants, it will also provide food and shelter for wildlife.
By collecting and holding water longer than a typical lawn or garden area, allowing it to soak slowly into the ground rather than running off, a rain garden keeps excess water from washing into storm drains or nearby waterways. Its plants act as natural filters, capturing contamination carried in water coming off impervious surfaces such as rooftops, roads, driveways, parking lots, and compacted lawn areas before it can reach the watershed. A rain garden also decreases other harmful effects of storm water, such as soil erosion and sedimentation of streams and rivers.
Installation is fairly simple. Here are a few key points to ensure success.
- Choose a sunny or partly shady location more than 10 feet from the house, but not over the septic system or near wells or underground utilities. Don't choose a spot where the drainage is already poor; you want the water to soak in to the soil relatively quickly, not stand for long periods.
- Calculate the percentage of slope to gauge proper depth: if less than four percent, make the rain garden 3 to 5 inches deep; if between five and seven percent, make it 6 to7 inches deep; and if eight to twelve percent, make it 8 inches deep.
- Depending on soil type--sand, silt, or clay--the garden should comprise 100 to 300 square feet, with more space allowed for slower draining soil. Configure the garden so it is twice as long as it is wide.
- When shaping the garden, placing extra soil on the downhill rim to make a berm.
- Select mature plants with well-developed root systems.
A couple of years ago, I worked with other Master Gardeners to construct a demonstration rain garden at a local park. Some of the plants we used included daylilies (Hemerocallis), purple coneflowers (Echinacea purpurea), irises, butterfly weed (Asclepias tuberosa), Virginia sweetspire (Itea virginica), and inkberry holly (Ilex glabra).
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