When water from a heavy rainfall moves over your yard, it can carry away soil – particularly, the more nutrient-rich topsoil – along with it. Moving water is the most prominent cause of erosion, which can kill plants by sweeping soil away from their roots and denying new seeds and plantings the opportunity to become established. Over time, erosion can alter the overall appearance of your landscape (for example, by transforming the borders of a garden) and even undermine the foundation of structures like your home.
On a steep slope, gravity will assist water in carrying more soil away with it. If the soil is loose, this factor will also greatly contribute to the rate of erosion. Facilitating the drainage of water on your property – for instance, by digging a dry well or grass swale – can make a difference with regards to runoff, but it can’t adequately address the problems caused by steep slopes and shallow soil. If you have a garden on an incline, you’ll probably want to be more proactive. But addressing the threat of erosion doesn’t necessarily require that you make drastic changes to your yard. There are simpler remedies that can be tried first.
Plants are your strongest erosion deterrent. A bed of plants covering a given area will resist the leeching of soil at every level. Their leaves (particularly those of trees, shrubs, and hardy groundcovers) will shield the ground and absorb a lot of the impact of falling rain so that it doesn’t pummel the soil. And their roots will cling to the soil tenaciously, holding it in place, and also absorb some of the water that penetrates into it. Using plants for erosion control can also leave you with a more natural look than what you’d have, for instance, with a retaining wall. Choose plants whose root systems reach deep into the ground – four inches or more. Some varieties that work well include catmint, sedum, mondo grass and English ivy.
If you’re dealing with a relatively gentle grade, you can use organic mulch to slow erosion. Mulch, however, tends to be gradually swept downwards on steeper slopes. In such places, it’s better to use landscape fabric. The fabric stays in place as it protects and steadies the soil, and it takes years to break down. Modern landscape fabrics also keep the soil from drying out, allow water to seep in and fight weeds by denying them sunlight. You can easily cut slits in the fabric for plantings, and then cover unused areas with mulch and/ or stone.
If none of these measures proves to be a lasting solution – or if you’re planning on making additions to your landscape anyway for aesthetic reasons – you might consider transforming problematic slopes by building terraces, steps (of either stone or wood) or retaining walls. These kinds of structures not only remedy erosion problems but can also exist as features of interest and beauty in your landscape in their own right.