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Sunday - October 05, 2008

From: Harpers Ferry, WV
Region: Mid-Atlantic
Topic: Erosion Control
Title: Erosion control for steep slope in West Virginia
Answered by: Barbara Medford

QUESTION:

I live in Zone 6 (Eastern Panhandle of WV). I have a rocky, claylike steep slope (30-40% grade, about 50 feet wide and 20 feet long, it sits in the afternoon sun). So I need to plant erosion-control plants (we just moved here, so I have to move fast as winter approaches). I considered blue rug juniper, but I do not have the budget for that number of plants. Also, seeing as I will have major erosion problems this winter, I need a plant that can set down its roots quickly, so if I did do the blue rug juniper, I'd have to purchase some sort of landscape fabric that would deteriorate over time as the plants grew in. Any ideas?

ANSWER:

First, the good news (at least as far as we are concerned), Juniperus horizontalis (creeping juniper), is a native to North America. At the Lady Bird Johnson Wildflower Center we focus on plants native to North America and to the area in which they are being grown, because they will need less fertilizer, water and maintenance. The "Blue Rug" you refer to is a trade name assigned to this plant, no doubt to enhance sales. The plant is not native to West Virginia, but seems to mostly populate areas to the north, really north, like Northern Canada. However, according to this Floridata article, "Juniperus Horizontalis," this juniper will grow in other, warmer parts of the country. The bad news is that it is slow-growing (but long-lived), susceptible to juniper blight, often infested with spider mites and bagworms, and a real pain to weed. As you point out, time is your biggest enemy here.

We are plant people, and don't know much about how to prevent erosion except by planting plants with good root systems that can grab the dirt and hold it. Ordinarily, we would recommend grasses, because they seem to be designed for erosion control, with fibrous roots and year round appearance. There again, they would need to be seeded, and if they were seeded now, they would winter over and then come up. Meanwhile, the winter rains you are apparently concerned about would have washed a great many of those seeds somewhere you hadn't planned on. We will suggest some native grasses, but that is probably not going to be the immediate solution you need.

You asked about landscape fabric; again, out of our expertise, but we found this Suite 101 website, "Use for Landscape Fabric" that has links to a number of articles about just that purpose. There is a possibility that it could even be used to hold the slope, with stakes to secure it in place, until Spring, at which time you would have to punch holes in it to plant whatever you decided on.

So, let's play "What's the worst that can happen?" Is this a slope that has been there for some time, or is it a product of grading done in building your house? If it was an existing slope, caused by a hilly terrain, it has held on this long and should be able to last until Spring without severe damage. If, however, this is a newly-graded slope with no natural vegetation on it, and you have heavy seasonal rains in West Virginia, it could slump quite a bit. Would this affect your foundation or pour mud into a street or somewhere else you don't want it? Is there any possibility that you could do an emergency "fix" by having some regrading done, or inserting landscape timbers? If it is very serious, you probably will need at some point to consider some sort of terracing or retaining walls; there is only so much plant roots can do and they have to grow quite a bit and spread to be really effective. We absolutely understand the budget constraints of moving into a new house and needing to do everything at once, so you may have to assign priorities according to how worried you are about erosion.

As promised, we are listing some recommended grasses and grass-like plants (sedges) for your area. All of these are native to West Virginia. This is probably a project for Spring, and if you have put down landscape fabric, it will have to be taken up again in order for the seed to make good contact with the soil. If you come to this point, go to our Native Plant Suppliers section, put your town and state in the "Enter Search Location" box, and you will get a list of native plant seed suppliers, nurseries and landscape consultants in your general area.

Andropogon gerardii (big bluestem)

Andropogon virginicus (broomsedge bluestem)

Carex blanda (eastern woodland sedge)

Calamagrostis canadensis (bluejoint)

Carex hystericina (bottlebrush sedge)

Carex texensis (Texas sedge)

Deschampsia caespitosa (tufted hairgrass)

Schizachyrium scoparium (little bluestem)