The Best Grasses for Controlling Hillside Erosion

Seasonal

• Native grasses offer coverage that blends with other native plants. Annual grasses, such as rye grasses, grow quickly from seed. They offer seasonal control, but help hold hillside erosion in check until permanent grasses take root. Native rye grasses germinate in less than a week and cover ground quickly. Their seed heads provide food for birds and wildlife. These seasonal grasses provide cover for young perennial grasses and often reseed themselves for the following year.

Tallgrass

• Tallgrass prairie grasses, once covering the central North American prairies, are warm season grasses. The Big Four, sometimes called the Four Horsemen of the Prairie, are Big bluestem, Little bluestem, Indiangrass and Switchgrass. Cultivars of these native grasses adapt well to hillsides. Their roots grow up to 17 feet into the soil. The grasses form clumps typically 5 feet wide and 5 to 6 feet high. Native to dry prairies and surviving on rainfall, these sturdy grasses tolerate wind, drought, heavy rain and steep slopes. Switchgrass tolerates wet areas as well as dry, holding slopes around ponds and creeks. These grasses can be mowed if desired or left in their natural state. They partner well with wildflowers for a scenic hillside.

Decorative

• Many ornamental grasses offer erosion control and decorative foliage. From short green turflike liriope grass to tall fountain grass, these ornamentals hold soil either through sturdy roots or rhizomes. Rhizomes form a vegetative network over the soil, preventing water from washing away soil and wind from lifting off topsoil. Cultivars change color with the seasons or offer flumes and flowers. Many form dense root and stem clumps that resist erosion-causing rodent tunnels. Many mature as dry winter plants that keep snow from drifting down hillsides or across roads.

Maintenance

• Hillside-gripping grasses are tough but benefit from occasional fertilizer such as a 10-10-10 balance. Mow as necessary to prevent fire hazards from the dry grass. An annual mowing removes dead foliage before spring renewal. Some grasses need light irrigation until established and during drought months. Divide clumping grasses periodically to prevent overcrowding. Tie clumps together with twine and then use shears to trim the clump to 12 inches or less in height. Cut back grasses when they invade cultivated landscapes.