What Is a Berm?
A berm is simply a rounded mound of soil (and, sometimes, fill) built upon an otherwise level patch of land to improve the design of a property. The fact that a berm is rounded is what distinguishes it from a raised bed. The latter has a flat surface and a rectangular shape.
Supplies to Build a Berm
Flexible garden hoseFlourSpade, shovelSteel rakeTamping toolWheelbarrowFill, such as rubble or gravel (optional)Clayey soil (optional)TopsoilMulchEdging material (optional)Boulders (optional)Plants
Basic Berm-Building Rules
There are few hard-and-fast rules in building berms, but beginners should use the following guidelines:
Make the slope gradual. Not only will this look more natural, but it will also help you prevent erosion. Don’t try for a height much greater than two feet, and expand the base about five feet out in width for every one foot the berm rises up. The 5:1 ratio is just an average, though, because you should vary the slope to create greater interest. Give the berm more than one peak, and avoid putting the highest peak in the center of the berm. Berms are more interesting if they are shaped like kidney beans or crescent moons than if they are circular. Be mindful of potential drainage issues at all times while planning and building your berm. Remember that erecting such a structure in your yard can have the effect of channeling rainwater towards areas of the land where it was never intended to go. This is why it is better for a beginner to build a berm that is of relatively small size and to stick to building just one berm. In the worst cases, you may have to install a drainage system. Dirt piled up willy-nilly may well erode when it rains unless you pay attention to how you layer your berm, assuming that you want to avoid the cost of a berm composed totally of topsoil (loam). To save money, use topsoil as a top layer (it is great to grow your plants in), but use clayey soil as a second layer, not a fill such as gravel or rubble. Clay is a type of soil more impervious to water than is fill, so your topsoil won’t percolate through it. Underneath the clay, use fill to build up the bulk of the base.
Step-by-Step Instructions to Build a Berm
In the planning stages, first be sure to call “Dig Safe” Phone Number (or its equivalent in your area) so that the presence of underground utility lines, etc. on your property can be marked. The location you choose for the berm will depend on the function it will serve for you. If it will serve as a planting bed for a flower border intended to be seen from the street, choose a location close to the street. Regardless of the exact location, let’s assume that you will be building the berm in what is presently a lawn area. Here’s how to proceed:
Berm Building Tips
Edging material and boulders are optional supplies here. Here’s how they can be useful:
Reasons to Build a Berm
At the most basic level, incorporating a berm in an otherwise flat yard is about raising the viewer’s eye level. Flat expanses are boring, and injecting a vertical element makes such a space more interesting. But, in addition to this most fundamental of reasons for building one, consider that a berm can benefit a landscape by, for example:
Functioning as a planting bed in an area with poor soil (as could a raised bed, as well) Providing a windbreak and/or noise barrier Serving as a privacy screen in conjunction with the plant material used Raising small plants closer to eye level so that viewers can appreciate them more fully
