An easy method to adding interest to landscaping is simply by adding some height to the landscape. Height is often overlooked or created without any thought to its role in the artistic value of the design. However, it can and should be given some thought as a design element in landscapes and especially in dull flat yards.
There are several ways to create height in a landscape. Plantings themselves create a second level. Generally, height is created by retaining walls, walls, arbors and other hardscapes, plants, and berms.
Berms in landscaping are small sweeping hills that are usually created for the purpose of creating height and interest. They work well in landscape areas that don't necessarily call for damming or retaining walls. A good example would be in the middle of a large lawn area. Berms can help add height, levels, and interest to yards and landscapes that would otherwise be dull and flat.
I've never given much thought to how I create a berm or have I been asked how to make a berm correctly until recently. I all of a sudden got a slew of emails requesting information on how to build a berm correctly.
While there's no trick, special art, or rules to creating berms, I guess there is some method and a way to keep them from looking like odd bumps in your yard. These are just the simple "rules" that I can think of. They're not written in rock.
A berm should be at least 5 to 6 times as long as it is high and should gradually "feather" into the yard. If you create a two foot high berm, make it "feather" 12 or so feet long into the yard.
depth is, I think, is just a matter of feel for what looks natural and good. A 2 foot high, one foot wide hill would have too much of a slope to hold ground cover and would look very unnatural. The width should also "feather" into the yard.
Oftentimes, berms occupy and fill corner areas and a lot of times have a crescent shape open toward the yard. However, shape can be anything that fits, is creative, or follows the flow of the yard. Berms in lawns can be continual, connecting, and flow throughout the yard.
In bed areas, boulders or larger rocks can be placed into the berm to give it a more natural look, places to plant around, and aid in holding smaller ground cover in place.
I hope this helps.