Berm Styles in Landscape Designs
A berm is a mound of earth with sloping sides located between two areas of approximately the same elevation, according to the University of Minnesota Sustainable Landscaping Information Series. You can use berms in your yard to direct or contain water, reduce erosion, provide privacy, screen out noise, add interest to a flat landscape, separate different areas or direct foot traffic.
Water and Erosion Control
Keeping rainwater on the property to conserve water is one of the most common uses of berms. This is generally achieved with a combination of swales -- wide, shallow depressions -- and low berms. To form a low berm, dig a swale at approximately right angles to the flow of water, and pile the soil removed from the swale on the downhill side of the swale. Then plant high water-use plants in the swale and lower water-use plants on top of the berm.
Privacy Screen and Noise Control
To make a front or side yard more private, build a waist-high berm with small trees and shrubs on it. People seated on the inside of the berm will not hear street noise and will not be seen from the street. The berm should gradually feather into the landscape and should not be so steep that soil and mulch washes down from it. The base of the berm can be made with fill or rubble covered with topsoil to reduce expenses.
Rock Gardens and Flower Beds
A rock garden berm should look as natural as possible. Make sure you use all rocks of the same geologic type. Partially bury them in the soil so they look like they form a substrate. Mounding, clumping and creeping plants spread between the rocks should also be placed in natural-looking formations. Berms can also show off mini mountain meadows or English cottage gardens. The landscaping on the berm should blend with and complement the other landscaping and the style of your house.
Separation and Traffic Control
A berm between an adult sitting area and a play area for children defines the spaces and provides privacy without completely separating them. Next to a parking area, a berm will encourage people to take a path or walkway rather than trampling the landscaping. Berms can also keep people from cutting across a corner lot or going through a yard to reach a public area such as a park. Use plants to emphasize the form and purpose of the berm.
Septic System Mounds
If your home has a septic system and there is less than 3 feet between the system and saturated soil, the system must be in a mound. The mound can be treated as a berm and landscaped, with some restrictions. Use plants that will survive on the natural rainfall of the area. Do not plant trees on the mound, and do not fertilize or irrigate it. Inspect the mound regularly. Check soil depth, look for burrowing animals and replace plants that are not thriving.
- University of Minnesota SULIS: Building Soil Berms
- Sunset: Privacy Without Walls
- University of Minnesota: Landscaping Septic Systems
- Gaia's Garden: A Guide to Home Scale Permaculture, Second Edition; Toby Hemenway
Lynn Doxon has a Ph.D. in horticulture, is a retired cooperative extension specialist and teaches courses in urban farming. She is the author of three books: "The Alcohol Fuel Handbook," "High Desert Yards and Gardens" and "Rainbows from Heaven." Doxon wrote the Yard and Garden column for the "Albuquerque Journal" and numerous magazine and newspaper articles and cooperative extension service guides.