Trees & Grasses That Prevent Erosion

Trees

• Certain trees should not be planted in erosion areas, such as certain types of manzanitas, because they have shallow root systems. However, trees like Douglas fir, Pacific madrone, black locust, bristly locust, persimmon, eastern red cedar, flowering crab apple, northern bayberry, Washington hawthorn, black gum and scarlet oak greatly improve eroded sites and give wildlife cover and food. Gardeners may also prevent erosion by planting native trees that grow well in the soil type of the area and climate.

Grasses

• Some grass types encourage soil erosion, such as red fescue. The wrong type of grass adds to the weight of the surface area and helps dirt slide down the slopes. Grasses that help prevent soil erosion include inland sea oats, Virginia wild rye and side oats grama. When using grass to control soil erosion, plant a grass type that can survive your climate. For example, cool-season grasses are grown in the northern parts of the United States, while warm-season grasses are grown in southern regions.

Planting by Streams

• Planting to control soil erosion near streams is handled differently than on inland slopes. Gardeners must not plant grass 20 to 500 feet away from a stream. Trees and shrubs are better equipped to handle the soil erosion around streams, because their root systems are more extensive. Plant silky dogwood, rhododendron, silky willow, red maple, tag alder, black willow, sycamore, yellow root and ninebark. Avoid mowing any grass type that you have growing near a creek bed.

Other Factors

• Oftentimes, gardeners use mulch around their trees to add an attractive quality to the eroded area and prevent weed growth. Black plastic is used on top of eroded areas. However, black plastic does little to prevent soil from sliding down the slope and is often degraded by the sun. Furthermore, straw mulch is a misguided attempt by gardeners for controlling soil erosion. Straw is effective for the first rain and then is sent down the slope. Mulch such as rocks, pine and oak leaves are good choices for using around trees.