A creative way to add height and interest to a landscape is to build a berm, especially if your customer’s lawn is fairly flat.
Berms are mounded hills of dirt constructed for blocking out unwanted or unsightly views, creating a subtle sense of privacy, directing or redirecting drainage and foot traffic, emphasizing a particular focal point or adding raised elements to the garden.
Now let’s not confuse berms with the infamous mulch volcano. Where mulch volcanoes are eight to 12-inch piles of mulch stacked around the trunk of a tree, berms are mounds of soil that can sometimes have a small layer of mulch spread over the top. They may look very similar at a first glance, but the two are very different.
When presenting the idea of a berm to your customers, keep a few of these tips in mind when explaining the uses and benefits of berms.
Overall, creating a berm isn’t difficult. When constructing a berm, you typically will use some sort of fill material like plant debris, sand, soil or rubble, and this material can be used to make the bulk of it. As long as the material is capable of retaining stability without deteriorating, it can be used as the fill material. To ensure more vigorous plant growth, it is recommended that you incorporate compost into the soil you do use.
Before ever starting on the berm, be sure you and your customer have a plan in action. Talk to them about drainage options within the area that surrounds the berm, as it could redirect runoff to other areas, affect drainage patterns or encourage pooling after it rains.
Typically speaking, berms should be about four or five times as long as they are high. They will then gradually trail off or spread out into the lawn. There are multiple ways to create berms, and they can vary in size and can have more than one peak. They can be as deep as you and your customer want them to be, but they are typically no taller than 18-24 inches.
Berms can be formed into any shape really, but for a more natural look try sticking to the curving shape. Berms can run and flow throughout the lawn, or you can edge them in stones, plants and more to add a bit of flare to them. When you add a border to the berm, it can also help cut down on the soil eroding into the lawn.
Begin the process by outlining the shape of the berm with chalk, spray paint or even flour, just as you would do with any garden bed. Remove the sod and load the bottom of the berm with whatever fill you’ve chosen and pack down around it with soil. Keep piling up the soil to create a sloping mound, and remember when you are shaping the berm to pile the dirt into a shape that can mimic its surrounding landscape.
Berms, like all landscape elements, should look natural and blend in to enhance the overall design. When shaping and building the berm, take time to step back and see how it’s progressing and blending with what’s around it. If you see that it’s sticking out more than blending, take it in a new direction.
The transition between the lawn and the berm should be smooth and gradual, not bulky and awkward. The berm’s peak should also not be located in the middle, contrary to popular belief. To help keep more of that natural look and to help balance out the berm, the peak should be located more to one side. There can be more than one peak in a berm, but these peaks should vary in their sloping, width and height.
Be sure to tamp the berm once it’s complete to help prevent the possibility of collapse. Tamping also helps keep air pockets from pushing up plants and ultimately drying them out. It usually helps to water a brand new berm and follow that by tamping it again to make sure it doesn’t develop sinkholes. If this happens, just add more soil and continue tamping until it feels solid.
When choosing plants to go in your customer’s berm, remember that there will be microclimates within the berm that can affect the plants you select. Keep in mind that water will drain faster at the top of the berm, therefore choose plants that can tolerate drier conditions. On the flip side, plants that love moisture would enjoy being at the bottom of the berm.
With the sloping aspect of the berms, you need to also keep in mind the temperatures throughout the year. If plants are facing north or east, they will be cooler, and if plants are facing west or south they will be warmer.
Plants are going to really emphasize the berm’s form, so don’t be afraid to incorporate plants of different colors, textures, heights and forms. This will also help the berm last year round with such a wide variety of plants present. Plant shorter plants on the top and down the sides of the berm, and leave taller varieties for the back, depending on the overall shape of the berm.
Like we said earlier, berms do have a layer of mulch on top of the soil, but they are not completely made of mulch. With that said, finish the berm off with a healthy layer of mulch to help prevent soil erosion, provide insulation and slow down water. Shredded wood is usually a good option for berms since it is less likely to wash down in rain, and it also blends well into the surrounding landscape.