Creative Ideas to Landscape a Slope

Landscaping a slope creates extra challenges

Of all the landscaping projects a homeowner will face, properly landscaping a slope will probably be the most challenging. However, when properly designed and landscaped, a slope can add eye-catching appeal to the area and be a problem-free addition for years to come. Regardless of whether you are landscaping a slope in the backyard or front of the home, there are important factors you need to consider about the slope and the site’s conditions before the actual landscaping takes place.

Grade of the Slope

Knowing the grade of your slope is the first important consideration when choosing among landscape ideas for a slope. You can probably tell by looking at the slope whether its grade is steep or not. Mississippi State University defines steep slopes as having the land rise greater than 20 percent in angle. In everyday terms, this translates to a 2 feet elevation change for every 10 feet of area for walking. If you have a steep hillside with a rise is 50 percent or more, you won’t be able to rely strictly on vegetation to hold everything in place and will require a combination of landscape design methods to control erosion.

Slopes that range around 20 percent are usually more stable and not difficult to maintain, as you don’t have the same problems with erosion as you do with a steep slope. It is possible to stabilize slopes of 33 percent or less by establishing vegetative plantings on them.

Drainage and Soil Erosion

The biggest concern when it comes to steep slope landscaping ideas is water runoff from the top of the slope to the bottom, which causes soil erosion if not properly dealt with.  When conditions are especially windy and rainy, water drains from the top carrying down soil, mulch or rocks and depositing them at the base of the slope. In some cases, the runoff causes channels to form in the slope and can undermine the top’s stability.

Soil types also play a part in the erosion, as sandy types wash away easier than heavier soils like clay. In addition, you want to make sure the water drains away from your home’s foundation.

When dealing with a smaller slope, you don’t have these same concerns with drainage and erosion as you do with steep slopes, provided you use appropriate plants to help hold the soil in place. However, don’t fret because when it comes to ideas for landscaping a slope that is steep, you have various methods to deal with the problems of drainage and erosion.

Options for Preparing the Slope

Whether you are landscaping a sloped backyard or landscaping a sloped front or side yard, you have a wealth of options that fit into your design style and solve the problem of the slope’s steepness causing erosion. Those dealing with a smaller slope can also incorporate these landscaping ideas to add more elements to the outdoor space design. Regardless of if you are installing a low maintenance, low-budget bare rock garden or a front yard landscaping showstopper where the expense isn’t a problem, there’s an option for everyone.

  • Erosion Control Fabrics: There are various options in erosion control fabrics available to use on a steep slope, including biodegradable choices with prices fitting into everyone’s budget. Landscape fabrics for hillside gardens include coir netting, logs and mats, as well as selections in geotextiles. These products lay on top of the soil holding it in place.
  • Trenches: A relatively inexpensive way to control erosion and the flow of water, as well as add to the slope’s design is by creating properly placed trenches in the slope that direct the flow of water. Line the trench with river rocks to add to the design, as well as controlling the erosion. Drip irrigation is also an option, or you may opt for drought tolerant plants.
  • Retaining Walls: Although you might require a building permit depending on the size of the retaining wall, adding a retaining wall at the base of the slope will not only assist in stopping erosion but can work as a design feature. For those landscaping a slope on a budget, using pressure treated landscaping timbers is not only a low-cost option, but they will last for quite a few years. A more expensive but more natural look is creating a large-rock wall at the base of your hillside landscaping. In addition to a natural stone wall, you can use bricks, cinder blocks or concrete to form the barrier.
  • Step Terracing: Adding step terracing to your slope acts as several retaining walls spaced throughout the hillside garden. Terracing also creates garden paths, giving you access to your flower beds and colorful groundcover plants. Various areas on the slope are flattened, with landscape timbers or railroad ties supporting the sides of the step. Landscaping a terraced slope also has options to fit into everyone’s backyard landscaping design budget.

Planting the Slope

When it comes to landscaping a slope, plants do more than create attractive focal points. They do double-duty, controlling erosion while looking pretty. Those landscaping a slope on a budget have a wealth of options that won’t break the piggy bank. However, there are some key points about your slope you need to take into account before you go on a plant-buying spree.

Water runs downhill. Blame that darn gravity. So the soil at the top of the slope will have a tendency to be drier than the soil at the bottom, so choose plants accordingly.

Note the slope’s light conditions throughout the day. Are you landscaping a shady slope area or one located in the sun? Select groundcover plants that will thrive in the conditions.

Once you take all the conditions of the slope into account, now comes the fun part – purchasing your plants.

Purchasing Plants for a Slope

Since the plant’s root system works as soil anchors, holding it in place, it’s best to use a mix of plants including groundcovers, ornamental grasses and shrubs. You can also space annuals throughout the area and replace them with the change of seasons. Native plants offer you the least amount of problems, as they are used to the climate conditions in the area. You can usually find native plants ranging in grasses, flowering types and shrubs.

Grass and Mowing on a Sloped Yard

Mowing on a severe slope
Mowing on a severe slope may require ingenuity. This worker at the ancient Knowth burial ground at Brú na Bóinne, Ireland, uses a rope to mow a steep slope.

Grass is, of course, an option for landscaping a slope. But landscaping a slope will have two challenges, one short-term, and one long-term.

The short-term issue with grass on a slope is getting it to grow. Growing grass from seed is the less-expensive option, but that gravity thing rears its head again: Scattering seed on a slope and then watering it will cause the seed to wash downhill. The solution is to till thoroughly, seed as normal, but then cover the new seed with mulch, and water gently. Remove the cover when the grass seedlings emerge.

Growing grass from sod is more expensive but has the benefit of near-instant gratification. Lay sod at right angles to the direction of the slope, and use sod stakes to hold them in place.

Use proper mowing techniques. With riding mowers, experts say, always mow up and over the hill. Do not ride at a tilt where the top-heavy riding mower could tip over on its side. The U.S. Occupational Health and Safety Administration advises those with riding mowers to consult their owners’ manuals, which should specify how steep a slope the mower can tolerate. If no specific advice is available for your mower, set a limit of no more than a 15 percent slope.

It’s the opposite with push mowers, which are more bottom-heavy and can tolerate being tilted a bit more. Push mowers should run along the slope, rather than up and over it.

Although figuring out how to properly design and prepare your slope, especially if you’re landscaping a steep slope, can take a bit of time and preparation, the result is worth it. You end up with a functioning slope that is problem-free for years to come and can be the star of your property.

Joyce Starr

Joyce Starr

Joyce Starr has been writing on horticultural and landscaping topics for over 15 years. In addition, for the past 20 years she’s owned and operated a landscaping and design business. She shares her experience and passion for all things green through her writing.