Building a berm is a big project. Consider these basics while you’re planning, and you’re on your way to a stunning garden.
SIZE — As with any other large landscape element, make sure your berm is the right size for your needs. A small berm by the front door can add just as much “Wow!” as a bigger one by the street.
GRADE — Asymmetrical is the way to go. Natural-looking berms have the highest point closer to one side. The illustration above shows how gradually one side rises out of the ground, while the other side rounds off quickly. And change the height along the berm, especially if it’s a long one. It’ll be more interesting and more natural this way.
SLOPE — Don’t make it too steep! The 10-ft.-wide berm in the illustration is only 2 ft. tall at its highest point. This shallow slope allows you to mow the berm safely if you decide to grow grass. Plus, it won’t have erosion problems and you’ll find it more comfortable to work on.
SUBSTANCE — It would be expensive to buy enough topsoil to build an entire berm, and you don’t really need to anyway. Instead, use poor-quality soil or sod flipped upside down to build up the shape. Then top it off with a foot or more of good topsoil. Build the berm a little taller than you want the final height, as it will settle a bit. If you compact the sod or poor-quality soil, you’ll cut down on the amount of settling.