How to Landscape on a Slope
A slope or hill may be one of the things that most attracted you to your house, but once you've actually considered how best to landscape it, you may be reconsidering just how great a sloped piece of land is. There certainly are many difficulties that come into play with this type of project, but with the right plan it can be just as perfect as you dreamed it would be.
To get you started on your landscaping plan, we have three things to consider: First we'll cover how to best secure your sloping areas. Then we'll go over a plan and design that will get it looking it's best, and lastly, we determine what irrigation method will be best to support it all.
Fortifying the Ground
The first problem that often arises with gardening in an area that has both ups and downs, geologically speaking, is the question of just how sturdy the ground is. If it's loose and not compact or has ways for water to pool or drain too quickly, it can cause big issues, such as mudslides. It goes without saying that you'll want to secure the ground as best you can, and here's a few ways to do that:
1. Add a retaining wall to hold up the dirt behind or around the sloped area.
2. Use flagstone or other stone pavers to cover a portion of the slope. They must be spaced in such a way that water can still drip into the ground around them -- they shouldn't be butted up directly against one another.
3. Use woody plants that will deeply root and therefore secure the soil beneath it by holding the layers of earth together.
You can use all three of these techniques, or just one to help sturdy up your ground. It all depends on your design and the type of slopes, terraces, or hills you have in your landscape. As for plants that would help make the ground more cohesive, small shrubs would work perfectly. Some possible considerations are Common Snowberry, roses (native to your area), Red Flowering Currant, Twinberry, Vine Maple, and Red Twig Dogwood.
Other plants that root deeply and will work great are certain types of ground covers such as Deer Fern, Twinflower, Trailing Blackberry, Sword Fern, and Bunchberry.
Plants that help strengthen a sloping landscape can vary from state to state (the aforementioned are more specific to the Pacific Coast region). You can check with your local nursery for the best recommendations, or check out the USDA Natural Resources website and click on your state for plants native to your area.
Designing on a Slope
Once you know what types of things you have to do to ensure that your terraced landscape isn't going anywhere, you can start designing. Incorporate some or all of the ideas mentioned earlier in whatever way you think will best add to the overall look that you want and begin to draw it out. Your drawing doesn't have to be perfect or fancy, just a rouch sketch of what goes where.
Things to keep in mind while creating your design are the size of each type of plant or other material (such as rocks or decorative items) you'll be adding to the landscape. Using ornamental grass is also a good idea for areas that you're unsure what to do with but still want to look nice. Ornamental grass or ground cover will help keep weeds out of these areas, and since weeding is more difficult on a slope, filling in empty spaces is a wise thing to do.
For a beautiful backdrop at the top of your slope, consider small trees and shrubs like Lilacs, small Junipers or even a beautiful grouping of Fountain Grass. As your design moves down the slope, consider drought-tolerant plants native to your area since the water will have a tendency to run down and away from roots. For the bottom of the slope, add a fast-growing, wide-spreading, colorful ground cover for an eye-catching area.
Irrigation Tips for Sloped Earth
Your final consideration for a sloped landscape is one of the most important: irrigation. For this you will want drip irrigation and not sprinklers, which will cause surface runoff and not penetrate the ground. With drip irrigation, the water slowly enters the ground and won't run quickly, keeping the ground from shifting. To determine how long you should allow your drip lines to run you'll have to do a test run. For a smaller slope or incline, allow it to run for 20 minutes. For a larger slope you may try as long as 40 minutes.
Once it's done, check to see how moist the ground is around your plants. You don't want puddles of water or soggy earth; you want just enough water so that the ground around your plants is slightly moist. Once you have your timing figured out, set it on a timer and be sure to shut it off on rainy days so you won't have any soil erosion issues.
That's all there is to landscaping on a slope. It's just a mixture of the right plants and other natural resources, as well as being smart about how you irrigate.
Here's a final tip to help complete your garden: add a few stone pavers throughout your landscaping so that you can place some pots of annuals throughout the year. This way you will always have color in your beautiful sloped garden.