Rain Gardens: They're Not What You Think
Ever heard of a rain garden? They're gradually becoming more common, so you may be familiar with the term. When I first heard “rain garden” mentioned, I imagined a swampy wetland collecting stagnant water and mosquitoes and frogs, but that's not a rain garden.
A rain garden is just a shallow depression in the earth planted with native plants; after a rainfall it may have standing water for up to two days, but no longer. (In other words, it won't harbor mosquitoes.) If you see such a garden when rain hasn't fallen in the last forty-eight hours, you just notice a lovely native plant garden.
So if it looks like any other garden, what's the point of going to the trouble to plant a rain garden? There are several considerations that make a rain garden worth your time.
For one thing, rain gardens help to reduce rain runoff. In a natural area (one that hasn't been disturbed by human activity like constructing roads and buildings) where precipitation falls on vegetation or the soil, 10% of the water runs over the surface of the ground down to waterways and 50% lies on the ground until it seeps into the soil and eventually down to the aquifer. The rest, of course, evaporates or transpires into the atmosphere through the leaves of plants,
In a “developed” area, where most of the soil has been covered by impervious material (buildings, roads, sidewalks, parking lots, driveways, etc.), 55% of rainwater runs off to waterways and only 15% seeps into the ground. As more and more land is taken from nature to accommodate our growing population, we can expect the volume of runoff to increase.
Increased runoff suddenly entering streams and rivers after a heavy rainfall carries increased risk of flooding. We are well aware of the damage caused to human habitat and enterprise by flooding, but natural areas are also affected. Flooding tears away vegetation along streams and erodes their banks, destroying wildlife habitat.
Flooding always involves erosion of soil, but erosion occurs without flooding every time rain falls on slopes with bare soil. And construction of buildings and roads leaves soil bare for months. Eroded soil is carried to waterways or storm sewers and finally to the sea, lost to us forever. Sediment is a major pollutant in natural areas and in cities. In streams it changes the water flow, muddies water so animals can't find food, and destroys the little organisms at the bottom of the food chain, resulting in the population decline of fish and other wild animals. In cities, sediment can clog storm sewers and must be removed in water treatment plants before water is suitable for human consumption.
Other pollutants added to the soil by human activities, such as fertilizers, pesticides and animal waste from agriculture and gardening. Industrial wastes like salts, acids, solvents, and heavy metals, are picked up by runoff. If some of the runoff can be diverted into rain gardens, plants and the soil can remove many of these substances before the water reaches the aquifer.
Although some cities have reservoirs to meet the residents' water needs, most water for our homes, agriculture, and industry comes from wells drilled into the aquifer. As our population increases and more land is developed, we allow less and less water to reach the aquifer while drawing more and more water from it. This is clearly not a sustainable practice.
Rain gardens planted with native plants can help restore natural habitat for wild creatures, reduce flooding and erosion, remove sediment and other pollutants from water and return water to the aquifer to conserve it for future generations, while enhancing the beauty of our surroundings and our enjoyment of nature.
There are plenty of how-to resources for building a rain garden. One of the most useful I've seen is Publication #EB-101 from the University of Georgia. It's available in print or on line at http://extension.uga.edu/publications/detail.html?number=EB101&title=Rain%20Gardens%20in%20Home%20Landscapes.
If this isn’t a DIY project you want to do, you can of course hire a landscaper. Interview them first to verify they are experienced in planning and constructing rain gardens and if they are providing the plant materials be sure they understand you want only native plants in your garden.
Use perennial native plants that tolerate standing water for a short time and are also drought-tolerant—and there are many! Beyond that, choose plants as you would for any garden, considering size, flower and foliage color, blooming season and diversity. You'll enjoy the beauty of your creation while making a difference in our ecology.
Resources for Rain gardens
Resources for Rain Gardening
Rain Gardens in Home Landscapes: Bulletin 101 (pdf)in Gardens in Home Landscapes
Includes detailed information on construction of a rain garden
Rain Gardens for Home Landscapes
Note: Some of the above publications contain recommendations for plants that are not native to our area or even to North America. Please do your research and select only natives.
Plant Suggestions for Rain Gardens
Painted Buckeye Aesculus sulvatica
Yaupon Holly Ilex vomitoria
Sweetbay Magnolia Magnolia virginiana
Sweet Shrub Calicanthus floridus
Beauty Berry Callicarpa americana
Button Bush Cephalanthus occidentalis
Winter Berry Ilex verticellata
Dog Hobble Leucothoe spp.
Gallberry Ilex glabra
White Turtle Head Chelone glabra
Butterfly Weed Asclepias tuberosa
Spiderwort Tradescantia virginiana
St. John's Wort Hypericum perferatum
Cardinal Flower Lobelia cardinalis
Tall Ironweed Vernonia gigantea
Swamp Sunflower Helianthus angustifolius
Swamp Milkweed Aesclepias incarnata
Bee Balm Monarda didyma
Royal Fern Osmunda regalis
Little Bluestem Schizachyrium scoparium
Native Plants for Rain Gardens and General Planting - Some Sources
The Headwaters Master Gardeners supports the use of native plants whenever available. We asked several Master Gardeners for their recommendations on sources of native plants for your rain garden or other garden areas. Here’s what they came up with.
PLANT SALES are springing up all over the place this time of year. Several to consider and browse are:
Hall County Master Gardeners Spring Expo 2019, Chicopee Woods Agricultural Center, Gainesville, GA. Friday, April 5th, 8:30 am – 5 pm and Saturday, April 6, 8:30 am – 4 pm. Wide variety of vendors for plants, garden paraphernalia, speakers, etc. $2 per person admission. See hallmastergardeners.com.
Georgia Native Plant Society Spring Plant Sale, McFarlane Nature Park, 276 Farm Road SE, Marietta, GA. Saturday, April 6th from 10 am – 2 pm. 1,000s of plants, BYO wagon. See gnps.org.
And don’t forget the Headwaters Master Gardener Plant Sale at Celebrate Clayton 2019, Saturday, April 27th from 10 am – 5pm, and Sunday, April 28th from 10 am – 4 pm. In front of the Old Clayton Inn. Support your local chapter from White, Rabun and Habersham counties. Proceeds benefit our scholarship program.
OTHER SOURCES (not an endorsement, simply to get you started)
Lanier Nursery and Gardens, 4195 Schubert Road, Flowery Branch, GA. 470-290-5405 for days and hours, laniernurserygardens.com.
Goodness Grows, 332 Elberton Road, Lexington, GA 706/743-5055, email@example.com.
Piccadilly Farm, 1971 Whippoorwill Road, Bishop, GA 706/765-4444.
Niche Gardens, 1111 Dawson Road, Chapel Hill, NC 919-967-0078.
Georgia Native Plant Society Website at gnps.org has a long list of native plant suppliers.
Compiled by Lavon Callahan, Headwaters Master Gardeners