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Wednesday - November 21, 2007

From: Alexandria, VA
Region: Mid-Atlantic
Topic: Erosion Control
Title: Plants to control hillside erosion in Virginia.
Answered by: Nan Hampton

QUESTION:

Good Morning, Mr Smarty Plants, I need your advice and guidance. I live in a condo complex in Virginia and we have a hill/slope that is eroding. It also has two very nice tall trees that partially shade the soil. The soil is poor quality, many rocks, and washes away when it rains or snows. If my memory is correct, I had heard there was certain types of wildflowers that will hold the soil. What type of perennial wildflowers can we use that will grow in poor soil on a slope? Or do you have any other recommenations on what to plant on a slope/hill that would look beautiful and reduce errosion. Thank You for your assistance E. Hogan

ANSWER:

Good morning to you from Mr. Smarty Plants!

Grasses are what you need to get started with erosion control on your hillside. They are the best plants for controlling erosion because of the extensive fibrous root systems they develop.

Here are several attractive grasses native to Virginia that will grow in partial shade:

Bouteloua curtipendula (sideoats grama)

Chasmanthium latifolium (Inland sea oats)

Elymus canadensis (Canada wildrye)

Eragrostis intermedia (plains lovegrass)

Melica nitens (threeflower melicgrass)

Panicum virgatum (switchgrass)

Schizachyrium scoparium (little bluestem)

Tridens flavus (purpletop tridens)

The cheapest way to carry out your project is by sowing grass seeds. However, since you would be sowing the seeds on a slope, you will probably find that rain will wash the seeds away before they have had a chance to germinate. You might be able to find grass plugs available for sale. They will be more expensive than the seeds but would have a better chance of setting their roots before rain could wash them away. Another (alas, more expensive) possibility is to use erosion control blankets to stabilize the erosion area. The erosion-control fabric works by slowing the runoff water and allowing sediments to fall out rather than be washed away. Seeds are sown under the erosion-control material and grow up through the matting when they germinate. You can insert plants into the soil by cutting through the matting. The roots of the plants that are growing through the erosion-control material anchor the soil to stop the erosion. If you use erosion-control blankets made of biodegrable material, they will eventually disappear leaving the plants to control the problem. You can read about a stream bank stabilization project implemented by the Department of Environmental Services, Arlington, Viriginia. Although their problem was not exactly the same as yours, they did use the erosion control blankets with great success.

You might also consider sowing seeds of several wildflowers along with your grass seeds. Here are a few suggestions. You can find more from the list of recommended species for Virginia.

Coreopsis lanceolata (lanceleaf tickseed)

Echinacea purpurea (eastern purple coneflower)

Gaillardia pulchella (firewheel)

Hypericum prolificum (shrubby St. Johnswort)

Penstemon canescens (eastern gray beardtongue)

You can look for nurseries and seed companies that specialize in native plants for your area in our National Suppliers Directory.