Q: Spanning our backyard is a 60-foot-wide sloping lawn, in full sun, that’s dangerously steep to mow and an eyesore. What can we grow there that would be beautiful — without building any terraces? — Linda Larson, Atlanta, Ga.
A: Mowing on a slope is no picnic, but neither is transplanting, watering, pruning, dividing, or weeding. So whatever you choose to plant there should be capable of growing with minimal attention once its roots are established. One sensible strategy, involving only slight disturbance of the soil and risk of erosion, is to stop mowing, let the lawn grow long, and create a meadow of mixed grasses and perennials. If a meadow landscape doesn’t suit your taste, you can still use the no-mow approach as an interim strategy for establishing trees and shrubs. As the large woody plants mature, their shade will, in time, eliminate sun-loving grasses and perennials and create niches for woodland plants. Watching this natural progression will be a gratifying experience.
Because lawn grasses form a dense, almost impenetrable mat of roots, few seeds can germinate and grow there. You should begin by digging holes in the lawn and filling them with vigorous, deep-rooted perennial plants such as baptisia, butterfly weed, gayfeather, aster, goldenrod, and yarrow. Meadows look best with several ornamental grasses intermixed. If you decide to add grasses to your liberated lawn, buy (or start from seed) transplants of switch grass, Panicum virgatum, and little bluestem, Schizachyrium scoparium. In autumn, plant daffodil bulbs for spring bloom. For natural-looking drifts of vegetation, set out clumps of a single kind of plant, with a few individuals scattered across the bank. If the hillside has depressions or ridges, make some of the drifts follow their contours. An established meadow of mixed grasses and perennials will persist happily with little care, provided you patrol it once a year to uproot tiny unwanted trees, shrubs, and vines that may have sprouted from seeds dropped by birds. Early spring is the ideal time to do this, using a spade or a weeder with a long blade. You can keep the plantings tidier by cutting the vegetation once a year, before spring bulbs emerge, with a sickle-bar mower or a string trimmer.
If you wish to add trees and shrubs, Atlanta landscape architect Kerry Blind, of Ecos Environmental Design, suggests that you not line them up across the top of the slope, which would make the hill loom larger. Conversely, a row at the base of the incline will block your view and obstruct access. Instead, create a vista by concentrating trees and shrubs at the edges of the hill near the top of the slope and loosely interspersing them amid the perennials farther down. Within 60 feet of your house, plant only small to medium-height trees (15 to 30 feet) with attractive flowers and foliage. Natives that will thrive on a slope include crape myrtle, sourwood, and Eastern redbud. The list of suitable shrubs is even longer. Red osier dogwood is colorful both in leaf and when bare. Yaupon and dahoon hollies produce bright red berries. And there are many spreading junipers, some with blue or yellow foliage. As the trees mature and shady areas develop, add broadleaf evergreens such as azalea and leucothoe.
On a site like yours, small plants (perennials in 4-inch pots and trees and shrubs in the smallest containers available) will give the best results. Digging large holes and keeping big plants watered through the first year is a daunting task, especially since you’ll probably need to water at least once a week. Small trees and shrubs will take hold quickly and often outpace larger specimens within several years. They’ll also put less strain on your back and your bank account.