RAINGARDENS AND COMPOST
Why plant a rain garden?
Rain gardens provide for the natural infiltration of rainwater into the soil. This helps to filter out pollutants including fertilizer, pesticides, oil, heavy metals and other chemicals that are carried with the rainwater that washes your lawn, rooftop and driveway. Rain gardens also reduce peak storm flows, helping to prevent stream bank erosion and lowering the risk for local flooding. By collecting and using rainwater that would otherwise run off your yard, rain gardens allow you to have an attractive landscape with less watering.
How to Create a Rain Garden
- Locate a rain garden in natural depressions in the landscape near a downspout of the home.
- Use rope or garden hose to lay out the boundary of the rain garden in a curvy in shape with the longest length perpendicular to the slope of the land.
- The rain garden should be designed to hold about 6” of water above the ground surface.
- Ideally, locate the rain garden in such a way that a low berm on the downhill side of the rain garden will hold back the appropriate amount of water. A berm is a small earthen dam, no more than 12” high.
- The bottom of the rain garden should be as level as possible, so some minor grading may be necessary.
- Mix organic matter into the soil within the rain garden by spreading 2 to 4 inches of compost over the area and mixing the organic matter in with the existing soil.
- If the soil is acidic (has a low pH), lime should also be added to neutralize the pH of the soil.
- For soils with high clay content, it may be beneficial to remove about 1-2 feet of the soil and replace it with a more porous “rain garden soil.” A soil mix suitable for rain gardens is a mix of 50-60 percent sand, 20-30 percent topsoil, and 20-30 percent compost. The clay content in the rain garden soil replacement mix should be no more than 10 percent.
A rain garden can be the beginning of a more natural landscape for a homeowner. A more natural landscape can combine beauty with less maintenance and less need for chemicals. There is also a great deal of satisfaction from knowing that the landscape is keeping pollutants out of streams and lakes close by. To learn more about rain gardens or to find photos of demonstration sites, visit www.cleanwatercampaign.com or call 404.463.3259.
Special thanks to Dr. Rose Mary Seymour of the University of Georgia Cooperative Extension Service Griffin Office and Alfred Vick, Ecos Environmental Design, Inc.
Have you ever been frustrated by having to water your lawn only days after a rainstorm? Where does all that water go? Add in the watering restrictions, and it makes maintaining that green lawn even more challenging. It may be time to consider replacing some of your grass with a rain garden.
Rain gardens are landscaped areas designed to collect and utilize rainwater. They are a great way to reclaim rainwater from a roof downspout or driveway. Rain gardens allow more water from rain to soak into the ground to water plants and create a beautiful, low-maintenance landscaped bed. Typically about 30 percent more water from a rain soaks into the ground in a rain garden than in an equivalent area of lawn.
Rain gardens reduce stormwater runoff that carries pollutants from fertilizers and pesticides and debris washing from lawns and driveways into nearby rivers, lakes or streams. They also prevent damage to stream banks and reduce the risk of local flooding. In addition to being beautiful, they can provide valuable habitat to many birds and butterflies.
How Do Rain Gardens Work?
A rain garden collects stormwater, filters it through soils and plants and allows it to soak into the ground. A rain garden receives runoff water from lawns as well as rooftops or other hard surfaces such as driveways. The rain garden holds the water on the landscape so that it can soak into the ground instead of flowing into a street and down a storm drain. The plants, mulch and soil in a rain garden combine natural physical, biological and chemical processes to remove pollutants from runoff. Many pollutants will be filtered out and break down in the soil over time.
Where Are the Best Places to Locate Rain Gardens in the Landscape?
Rain gardens are best located in low areas if the yard where runoff tends to flow. While they should not be built next to a building’s foundations, rain gardens located near to impervious surface such as driveways, patios and sidewalks can easily capture the runoff from these areas.
A rain garden should be located at least 10 feet from the foundation of the house or other building. Sites with more than a 12 percent slope (an elevation change of 12 feet down per 100 feet in length) may not be suitable for rain gardens. Further, if you have a septic system, avoid planting a rain garden over top of the system.
What Plants Should You Use?
Finding plants for your rain garden is not difficult. Many native plants, available at your nearest nursery, are well-suited for your rain garden. Here are some suggested native plants:
|Red Maple||Acer rubrum|
|Black Gum||Nyssa sylvatica|
|Willow Oak||Quercus phellos|
|Bald Cypress||Taxodium distichum|
|River Birch||Betula nigra|
|Musclewood / American Hornbeam||Carpinus caroliniana|
|Green Ash||Fraxinus pennsylvanica|
|Sweetbay Magnolia||Magnolia virginiana|
|Virginia Sweetspire||Itea virginica|
|Summersweet Clethra||Clethra alnifolia|
|Common Winterberry/Winterberry Holly||Ilex verticillata|
|American Beautyberry||Callicarpa americana|
|St. John ’s Wort||Hypericum fasciculatum|
|Perennials, Grasses and Groundcovers|
|New England Aster||Aster novae-angliae|
|Broadleaf Uniola/Indian Woodoats||Chasmanthium latifolium|
|Joe-Pye Weed||Eupatorium fistulosum|
|Swamp Sunflower||Helianthus angustifolius|
|Scarlet Rosemallow/Swamp Hibiscus||Hibiscus coccineus|
|Cardinal Flower||Lobelia cardinalis|
|Cinnamon Fern||Osmunda cinnamomea|
|Royal Fern||Osmunda regalis|
|Golden Ragwort||Packera aurea|
|Yellow Stargrass||Hypoxis spp.|
|Swamp Milkweed||Asclepias incarnata|
|Narrowleaf Dragonhead||Physotegia angustifolia|
|Blackeyed Susan||Rudbeckia hirta|
|Red Columbine||Aquilegia canadensis|
|Clubed Begonia||Begonia cucullata|
Compost: From Golden Leaves to Gardener’s Gold
Compost is often referred to as “Gardener’s Gold” because of its ability to help plants grow. If you’ve ever been in a forest and peeled away the top layers of leaf litter on the ground, you will have seen a rich layer of this black, earthy, sweet smelling, moist material called compost. Compost, when mixed in with soil, improves soil structure, adds a wide variety of minerals and nutrients, and improves the soil’s ability to retain moisture.
Composting is the earth’s way of naturally recycling old plant material and you too can use this process in your own back yard to manage your yard waste. So, this fall, why not try composting all those fallen leaves and by next spring you too could be mining “Gardener’s Gold” in your very own backyard.
For information on how to compost call Gwinnett Clean & Beautiful at 770.822.5187 or visit their web site at www.gwinnettcb.org, click on the blue “Issues & Actions” button and select composting from the drop down list.