Photo by S. Cory Tanner
A variety of ornamental grasses and perennials, like these in Greenville’s Falls Park, can stabilize a steep slope and make an attractive display.
Steep, sunny slopes frustrate plenty of gardeners. These hillside challenges offer up one problem after another: hot, dry locations that are awkward to maintain, with poor soil and chronic erosion. Without vegetation, they can deteriorate into unsightly wastelands.
For years, the standard advice has been to plant juniper groundcovers or turfgrasses on these sites. Junipers are certainly tough enough to survive slope conditions, but they give landscapes a dated look, and they tend to allow weeds to poke up in between. If invaded by a single pest or disease, such as root rot, a juniper bed will turn into a swath of dead sticks in short order. As for turfgrasses, they must be mowed with regularity—a chore that is downright dangerous on a steep slope.
I say, ditch those junipers and lawn grasses in favor of a variety of attractive and easy-to-maintain ornamental grasses and perennials. Ornamental grasses, especially native species, are well adapted to enduring sunny slopes. Most can survive on low levels of soil nutrients and are drought tolerant once established. As a bonus, they have dense, fibrous root systems that are great for stabilizing soil and reducing erosion.
Grasses come in all shapes, sizes and colors. The wind blowing through grass leaves adds graceful movement and a pleasant sound to your landscape.
A few years ago, these grasses were hard to find in the nursery trade. But today, some are widely available, and you can even find multiple cultivars for most species. Some good options for slopes are switchgrass (Panicum virgatum), Indian grass (Sorghastrum nutans), little bluestem (Schizachyrium scoparium), weeping lovegrass (Eragrostis curvula), feather reed grass (Calamagrostis x acutiflora) and pink muhly grass (Muhlenbergia capillaris).
You might have some success with seed mixes, but you’ll likely enjoy greater success in establishing these plants by transplanting from containers or small plugs, as long as the plants are irrigated through their first summer.
Consider creating a wild meadow look by mixing different grasses at random in your plantings. Or, mass several plants from a single species in a large swath, so it’s easier to appreciate the individual attributes of each grass.
Sun-loving perennials and bulbs may be interspersed to provide extra color and multiple seasons of interest. Flowering perennials that look great among ornamental grasses include black-eyed Susans (Rudbeckia), coneflowers (Echinacea), butterfly weed (Asclepias tuberosa), false indigo (Baptisia), goldenrod (Solidago) and a variety of salvias. A mix of species will increase the biodiversity of the slope, turning it into a hotbed of butterfly, bee and bird activity.
Because slopes are commonly created from a landscape cut or fill during construction, they are usually composed of very poor soil. Perform a soil test before planting, and make the necessary adjustments. As always, organic matter (compost) will further improve the soil, increasing the health of your planting. Add a 2- to 3-inch layer of organic mulch (shredded hardwood or pine straw) to reduce erosion, conserve soil moisture and prevent weeds.
Other than watering during establishment and fertilizing occasionally, the only care these plantings will need is periodic weeding, focused on removing large weeds and woody plants that invade, and an annual mowing. Cutting back the grasses once a year, typically in February or March, will help keep the patch tidy and manageable.
A mix of ornamental grasses and perennials will have fewer pest and disease problems than a monoculture of junipers or turfgrasses, and it enhances wildlife habitat. Instead of a boring mat of green, you can enjoy a living, breathing, prairie-style landscape on your slope.
S. Cory Tanner is an area horticulture agent for Clemson Extension based in Greenville County. Email him here.
_____
Get More
For a full listing of species of ornamental grasses and care instructions, see the HGIC 1178 fact sheet “Ornamental Grasses.”