Clients frequently approach me with this question: “I have a steep embankment, which I hate to mow, got any ideas on how to deal with it?” Well, there are several good solutions that don’t involve string trimmers, herbicide, and heartburn for the rest of your life. In fact, there are several species of plants that can turn an eroding embankment into a stable slope.
The simple fact is that if your bank is too steep it will erode regardless of what’s planted on it. So before you try to plant, make sure that your bank is no steeper than a 40% grade. If you’re dealing with a slope that exceeds 40%, you should reduce the slope by excavating it from the top, or by building a retaining wall at the bottom.
Having good soil is crucial to getting plants to take root on your bank to prevent erosion. Most of the steep embankments I have planted had terrible soil because they were a product of excavation. In situations where you have a bank made up of poor soil, you’ll need to add some topsoil or work in some compost. However, you should never use a tiller to work in new soil or compost. Tilling will loosen the soil too much, causing the bank to erode even more. Use hand tools only to work the soil of your bank. They’re a little extra work to use, but the benefit of retaining the integrity of your bank is well worth the effort.
When it comes to selecting plants for your embankment, you have two options – ground cover (plants that remain short but spread quickly) or shrubbery and small trees. Ground covers I like to use include Japanese Pachysandra (Pachysandra terminalis), Periwinkle (Vinca minor) and Lily turf (Liriope muscari). Each of these plants is vigorous and evergreen. The first two do well in shade to partial shade, while Lily turf, depending on the variety you choose, can do well in shade or sun.
If you’re interested in going to the tree and shrub route, there are even more options. Winter Jasmine (Jasminum nudiflorum) has a thick, cascading form and a bloom similar to forsythia. It spreads by layering (stem touches ground and roots), which is great for holding soil and preventing erosion. Although very cold hardy, it is deciduous.
Creeping False Yew (Cephalotaxus harringtonia ‘Prostrada’) is a low growing evergreen shrub with a soft texture. It is very tough, yet not quite as vigorous. It spreads 3-4ft and grows 10” tall.
Rock Spray and Willow Leaf Cotoneaster (Cotoneaster salicifolia) are good for banks too, however they have a bad habit of collecting leaves and trash. The Willow Leaf variety is evergreen and has a cascading form, which is great for growing over walls. Other plants I often use on banks include Creeping Euonymus, Currants, Rugosa Roses, Forsythia, Sweet Box, and Winter Green.
These species are great choices for maintaining a troublesome embankment. Consult your local landscaping professional to learn more.
Photo by Antonio Castagna
Photo via Wikimedia Commons