Three Ways to Salvage a Sloped Yard
There are many reasons to dislike a sloped yard. It’s hard to play on a slope. Landscaping choices are limited. And few things in life are as difficult as mowing a sloped lawn. Luckily, there are several ways to flatten or otherwise improve a sloped yard.
The first thing to do is to figure out if your slope is steep enough to require significant improvements. Generally, you need to improve the land—by adding a retaining wall, for example—if you have more than a 4% grade, or about a foot in height difference. Regrading, or leveling, may be enough in other cases.
The remainder of this article will cover three of the most popular solutions for slopes: creating a series of terraces, building retaining walls, and planting slope-inclined groundcovers or grasses.
Plants aren’t the only ones who can thrive on slopes—some people can, too. Just look at the Inca. Their steep surroundings meant that they had to farm on hillsides. Their solution? Terraces.
If your yard has a moderate rise over a long run (say, perhaps, a rise of 2.5 feet over a stretch of 100 feet), you can use terraces to create level areas. Basically, terracing creates a series of level garden beds.
You may use railroad ties, boulders, wall kits and many other materials for your terraces. (Avoid using railroad ties near edible plants.) Local salvage organizations may have the perfect quirky reclaimed materials for your terraces. As you design your terrace steps, think about how you can repeat shapes, such as curves, to create a visually pleasing expanse. To see how one landscape architect accomplished this effect in a desert environment, watch “Landscaping on a Slope.” As for landscaping terraces, consider choosing perennials that will cascade over the edge of the terrace.
Steep slopes and long expanses may require retaining walls to flatten them out. What differentiates a retaining wall from a terrace is its height—some built by professional contractors are over ten feet tall. However, homeowners can generally handle retaining walls of less than four feet in height.
You can have a contractor install a retaining wall for you, or you can do-it-yourself using interlocking wall kits. However, a few construction precautions must be taken to ensure that the final retaining wall is level and impervious to frost heave and other moisture threats:
1. Focus on the first course. Once you have a building permit and you’ve checked for utility lines, you can begin digging your trench for the retaining wall. The higher the wall, the deeper the trench must be to properly support it. (A four-foot wall will require a two-foot deep trench, for instance.)
Once your ditch digging is done, you’ll need to lay in the first course. Create a level surface with stone dust. You must check that your first course is level from nearly all angles—front to back, top to bottom, and side to side. This will ensure the resulting wall does not buckle or wave. Once the first course is in, you’ll be able to stack up the rest of the wall like LEGOs.
2. Plan for Drainage. Water will need to be able to run away from your wall, but you don’t want it seeping through the stones. Gravel or other drainage aggregate is typically placed behind retaining walls to allow proper drainage. Walls over three feet in height should have additional perforated drainpipes or toe drains alongside the first aboveground course of bricks.
To prevent muddy water from seeping through the face of your retaining wall, add landscaping fabric between the wall and the fill-in soil.
Ground Covers and Grasses
Certain plants have evolved to thrive on inclines. If yours isn’t a steep slope, you may be able to stabilize and beautify it through purposeful plantings. In general, plants like English ivy (which sends out roots along its stem) and clumping plants like grasses (which have many small stems coming from one base) do well on slopes.
Ornamental grasses are a good choice for gentle slopes. They have fibrous roots that help hold soil in place. Fescues, such as blue fescue and red creeping fescue, are beautiful grasses for shallow inclines.
Steeper slopes will require different plants, such as ivies and honeysuckle. If possible, leave some turf around the new plantings to help hold them in place until they are established. Periwinkle, French lavender and creeping myrtle make good blossoming groundcovers for slopes. To learn more about planting on a slope, see the Natural Resources Conservation Service page on Groundcovers for Steep Slopes.
With a little planning and a few helping hands, your retaining wall, terrace or groundcover will be in place in no time—and you’ll finally be able to use your yard as you wish.
~Colleen Welch, 2010