Rain Gardens

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

1. Locate a rain garden in natural depressions in the landscape near a downspout of the home.
2. 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.
3. 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.

1. A shallow swale or corrugated drain pipe (buried or above ground) will channel runoff from the roof downspout or paved surface to the rain garden.
2. The soil in the rain garden should be a loose, sandy organic soil that allows water to quickly soak into the ground to nourish plant roots and recharge the groundwater. A general rule-of-thumb is to have a soil that soaks in about one inch of water per hour. The following steps will help to achieve this:

• 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.

1. Establish a grass or groundcover border along the upper edge of the rain garden to slow down the runoff water as it enters the rain garden. Do the same over the berm to stabilize it as a border of the rain garden.
2. Plant drought-tolerant, wet tolerant, hardy plants. A mix of ornamental grasses, shrubs, and self-seeding perennials are good choices. See the list above.
3. Once plants are in place, cover the rain garden with a 3” layer of mulch. Shredded hardwood is a good choice since it is less likely to float away.
4. Remove weeds on a regular basis and replenish mulch as needed.
5. Important note: Plan on providing an “overflow” path for water to take if it keeps raining after the rain garden fills up. This path should be stabilized with a hardy grass or groundcover

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.

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:

Trees
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
Shrubs
Virginia Sweetspire	Itea virginica
Summersweet Clethra	Clethra alnifolia
Common Winterberry/Winterberry Holly	Ilex verticillata
Buttonbush	Cephalanthus occidentalis
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
Switchgrass	Panicum virgatum
Golden Ragwort	Packera aurea
Ironweed	Vernonia noveboracensis
Yellow Stargrass	Hypoxis spp.
Swamp Milkweed	Asclepias incarnata
Asters	Aster spp
Violets	Viola spp
Broomsedge	Andropogon virginicus
Narrowleaf Dragonhead	Physotegia angustifolia
Blackeyed Susan	Rudbeckia hirta
Loosestrife	Lythrum spp
Red Columbine	Aquilegia canadensis
Clubed Begonia	Begonia cucullata