Erosion Control in Shady Areas

Home Grown  by Keith Reed
Tall fescue, our “go to” turfgrass for shade in this region, is often times a less than ideal solution for erosion control. Extreme shade, lack of topsoil, high humidity, and hot summers all pose problems for this species. Consider the following options if erosion is an issue in your own landscape, especially in situations where taller plant material can be adapted for use on the site.

Liriope (monkey grass) is a great plant. However, it is so common that we often overlook its value for this situation. Once the plant matures, it forms a very dense mat highly resistant to erosion. While primarily planted for its foliage, Liriope does have a nice purple flower spike to add some interest to shady areas. Mondograss is a very similar plant, only smaller in size, making it more expensive and slower to establish.

Inland sea oats is another common plant that is often overlooked for this use. Inland sea oats is a bunch forming native grass with a very showy seedhead that is valued for its use in winter and cut-flower arrangements. The flat seedheads like to dance around in the wind and are quite attractive. If you have spent any time wandering along our area creeks, you have probably seen this plant.

Ajuga, also called carpetweed or bugleweed, is a low growing broadleaf plant. Ajuga has a very showy purple flower spike. It is available in many cultivars with a wide range of leaf colors. This plant may not perform well in every site, but if it likes the location, it makes a very dense groundcover.

Moneywort is another plant to consider, especially if adequate moisture is available. Moneywort is a very low growing plant that also forms a very dense mat. You should know that this plant is on the invasive species list in some states although it has not proven to be a problem in our part of the world. However, just to be on the safe side, it is probably best not to plant this if you are unable to keep an eye on it. In other words, don’t plant it along a creek or other riparian area where flooding could move it downstream.

Virginia creeper is a native vine that forms a dense mat in shady areas. This plant will grow up and into trees so it must be kept in check with occasional cutting back.
Many common types of mulch will float and follow the water, making them unacceptable for use in these situations. A few that resist this to some degree are cotton seed hulls, pine needles and shredded cypress. Cotton seed hulls will mat together and form a very dense barrier. There are no hard and fast rules as to the amount of slope/runoff these mulches will withstand so it is best to start small and see how it works in a run-off event before spending lots of time and money only to see it float down the street.

Be sure your maintenance practices are not contributing to the erosion problem. A common issue we see is repeated non-selective herbicide application, especially along fences and other hard to maintain areas, creating a bare ground situation. Any cover, even weeds, is always better than no cover when erosion is an issue.

For more information on this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at
keith.reed@okstate.edu, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.

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