Steepness of slope. For steep grades, use species that produce dense, fibrous roots to help prevent soil erosion. Few ground covers, other than grasses, tolerate repeated foot traffic. Drainage and aeration. Surface soils may appear loose and loamy, but heavy, poorly drained subsurface soil may be present.
Few ground covers thrive in poorly drained soils.
A heavy clay soil on a steep grade has poor subsurface drainage and poor aeration. Most ground covers require at least two years to establish themselves and become sufficiently dense to control weeds. At higher altitudes, most ground cover plants take three or more years to provide serviceable cover. None can be completely neglected even after the planting is well established. During abnormally dry periods, even established ground cover plantings benefit from supplemental water.