Many types of plants, including a grass lawn, can be used to stabilize and cover a slope, or hillside, to prevent erosion of the soil. Lawns typically need to be mowed many times during a growing season, though. And depending on the angle of the slope, a grass lawn can be difficult to mow, and may create a safety concern, too.
Other plant alternatives to using a grass lawn on a slope or hillside are low spreading evergreen shrubs and groundcover. These types of plants provide coverage above the soil, and their root system below helps to hold and stabilize the soil. They can also provide year-round interest and beauty. Plants that die back seasonally, like many perennials and wildflowers, or deciduous plants, do not provide the same benefits, leaving the soil vulnerable to erosion. And the appearance could look rather barren from late fall to late spring.
Many low, spreading shrubs (mature height of 2 feet or less) typically have branches that grow to cover a large amount of area. Some junipers can grow up to 10 feet in diameter as their branches send down roots into the ground. Growth rates vary – many are slow to medium.
Evergreen groundcovers, like English ivy and myrtle, grow by sending out new stems that root themselves in the soil; these roots also send up new shoots creating a full and attractive display of foliage. Check out the growth habit of the groundcover you want to use – some are more low maintenance than others.
The following list are just some of the many plants available that can provide soil stabilizing benefits along with enhancing the beauty of a slope, or hillside.
These are hardy evergreen plants that retain their foliage year round.
- English ivy (Hedera helix) Very traditional in appearance; looks great in formal settings; grows more aggressively and can climb; sun or shade
- Pachysandra (Pachysandra terminalis) Great for shade; low maintenance; non-climber
- Purpleleaf Wintercreeper (Euonymus fortunei ‘Colorata’) Green summer foliage turns a reddish or plum color in the winter; woody stems; grows more aggressively and can climb; sun or shade
- Myrtle (Vinca minor) An easy to maintain groundcover; has small perwinkle color flower in spring and summer; non-climber; sun or shade
Low Spreading Evergreen Shrubs
As a heads-up, know that some shrubs are slow-growers and it may take years for them to reach their mature width and their full potential to provide erosion control.
Juniper (Juniperus) – Many varieties of the juniper have a low, spreading habit, are great for erosion control, and can be used in a wide range of site conditions. Examples include:
- Blue Pacific Shore Juniper (Juniperus conferta ‘Blue Pacific’ ) Although a slow grower, it is a favorite of ours for its needle-like evergreen foliage
- Hughes Juniper (Juniperus horizontalis ‘Hughes’); 6-8 spread; 1-1/2′ height
- Skandia Juniper (Juniperus sabina ‘Skandia’); 6-8 spread; 1-1/2′ height
- Dwarf Norway Spruce (Picea abies ‘Pumila’); 3′ to 4′ wide; 4′ to 5′ height
There are low, spreading deciduous shrubs available, although they may not provide the best erosion protection. Also, the bare branches of these shrubs tend to trap more fallen leaves and trash during the winter months, and provide less year-round interest than evergreen varieties.
Every plant has its own growth rate, hardiness, and tolerances. Before buying your plants, check if your plant selections will be suited for: your locale, the site conditions of where you will use them (such as sun, shade, soil type, salt tolerance), and, satisfying the particular needs of your project. You may also want to consider the level of maintenance your plants will take to maintain a tidy appearance.
Soil Erosion Protection Materials
The plants that you select will take time to grow and fill in the slope/hillside area. In the mean time, an added temporary measure of erosion protection can be provided by using a natural fiber fabric, or by using mulch.
The natural fiber fabric is typically jute, or burlap. It is a 100% natural fiber, and will biodegrade within 1-2 years. It has a porous weave, and will allow air and water through for the plants you install. It comes in rolls in widths of about 3 feet, and in a variety of lengths. It is available at home improvement or hardware stores.
Another soil erosion control option is using a 3” thick layer of coarsely shredded mulch. We used this method on a client’s front yard slope (see photo below). From the house, the front yard was level for about 20 feet, then sloped at an approximately 45 degree toward the street, which presented a difficult area for mowing. The lawn was removed and replaced with a groundcover. The layer of coarsely shredded mulch was applied to control erosion of the soil while the groundcover had time fill in and cover the slope. Applying a new layer of mulch may be neccesary for the first few years. The mulch can also act as an attractive top dressing for the plant bed.
Depending on your project, you may want do a price comparison in regard to the needed quantities of the jute fabric versus the mulch, to see which material/method would be most economical for you, and beneficial in the long run.
Photo credits: betterOutdoorLivingatHome, Morton Arboretum