How to hold up a bank

Making a hillside garden from an eyesore slope 

STORY AND PHOTOS BY LAURA C. MARTIN

One of the most difficult of all landscape problems is a steep slope with poor soil. But, take heart! There are solutions that don’t involve kudzu. Mother Nature has blessed us with plants that will grow and thrive in every imaginable situation, including some for a steep hillside. With a little planning, a careful selection of plants, and a bit of work and effort to make sure the hillside garden gets off to a good start, you can transform an eyesore into the crown jewel of the garden.

Before you get out the shovel, there are several questions you need to answer. The first is to determine your goals. If you are simply trying to keep the hillside from washing down into the neighbor’s yard, then your plan will be different than if you are trying to create and establish a beautiful vertical garden.

No matter what your ultimate goal is, you will have to invest time and effort to accomplish it. Working on a hillside is not easy, so you want to do it as infrequently as possible. This means that it is critical for you to 1) get rid of as many weeds as you possibly can before you plant anything; 2) work with the soil, digging deeply and incorporating organic materials to create the rich, friable soil; 3) be sure to get enough water to the plants until they are well situated; and 4) be relentless in keep-ing weeds from getting a toehold. You want the plants to establish quickly, leap out of the ground with vigor and put down a vibrant root system that rapidly stabilizes the soil.

Choosing the right plants is necessary for creating a good, stable hillside garden. You may want to put grass on a hillside, but this comes with its own set of problems. As you may have heard, water runs downhill, meaning that it’s difficult to get water down into the root system of a sloping lawn. It’s also hard to mow on a hillside. If you are determined to have a grassy hillside, though, rather than using seed, place strips of sod horizontally across the slope. If you have a large area, you might want to invest in hydroseeding (where an emulsion that includes grass seed is sprayed onto the hillside).

If the slope is really steep, consider getting an erosion control mat, a woven blanket that keeps soil from washing away. There are many different kinds on the market, varying in size, price and effectiveness. Whatever you use, make sure it is permeable and biodegradable. Place the mats over the hillside, cut holes where you want to install plants, then mulch directly over the mat. This not only stabilizes the soil but also helps discourage weeds and retain moisture.

Another way to landscape a hillside is to create terraces by building retaining walls out of rocks or pressure-treated lumber. This solution can be as simple or as complicated as you like. You can create small, flat spaces by building a “mini-wall” with a single large rock or boulder. More elaborate walls will give you larger planting spaces and will keep the hillside from washing away.

Before you begin purchasing plants, determine the light conditions you have to work with. Is your hillside in full sun? Full shade? Partial shade? Be sure to purchase plants that are suited to your conditions.

In general, a combination of shrubs and ground covers is a good choice for planting on a steep slope. Whether your area is in sun or shade (or in between) there are a multitude of plants that should fit your needs.

Some of the best plants to use on a sunny bank include shrubs such as barberry, yew and upright juniper, and low-maintenance roses. Perennials and ground covers for this situation include sedum, dianthus, candytuft, thrift, daylilies and various ornamental grasses.

For a bank in the shade, try shrubs such as rhododendrons, mahonia and leucothoe, underplanted with pachysandra, creeping phlox, dwarf periwinkle (vinca), creeping juniper and various ferns.

Once everything is planted, be sure to irrigate well and then mulch heavily. Stay on top of the weeds, particularly during the first growing season.

Although it takes time and effort to establish a garden on a steep bank, it is a wise investment. You will reap the dividends from this treasured garden for years to come.

Laura Martin, of Atlanta, is the author of 26 books on gardening and nature crafts.