Use low-growing perennial plants and shrubs as groundcovers to cover slopes and rough ground or to replace high-maintenance lawns. Choose plants that thrive in your particular soil and climate.
First, calculate the number of plants needed. Space plants so that the distance between them is about equal to their maximum width. If plants are very slow growing, space them slightly closer. Spaced properly, most ground covers will spread and cover the soil surface between them by the third growing season. To determine a plant's maximum width, check with experienced nursery staff or reference books. Here's how to plant groundcovers.
Prepare the Soil. Eliminate all weeds and grass from the area before planting. For large areas, use glyphosate herbicide, a rototiller, soil solarization, or a rented sod-stripping machine to clear the area of plants and grass. Solarize the soil by laying clear plastic over cleared and moistened soil (so the sun's heating rays can penetrate and heat the soil). Seal the edges with soil, and leave the plastic in place for 4 to 6 weeks.
Space Plants and Dig Holes. To know how many plants you'll need at various distances, use the following as a guide: 100 plants spaced 6 inches apart cover about 20 square feet; 12 inches apart, they'll cover 85 square feet; and 18 inches apart, they'll cover 200 square feet. Arrange plants in zigzag rows so they are equal distance from their neighbors. Dig holes to the same depth as, and two to three times wider than, the plants' root balls.
Plant. Water plants thoroughly a few hours before planting. If weeds are severe, consider covering soil with a water-permeable landscape fabric (see Tips below). Tip each plant out of its pot without pulling on the stems. Untangle circling roots gently with your fingers. Place in the hole so that the plant will grow at the same soil level as it did in the pot. Spread the roots and backfill with the soil that was removed from the hole. Press the plant gently into place.
Water and Mulch. Water plants thoroughly after planting to settle the soil. Spread 2 to 3 inches of organic mulch, such as shredded bark. If using landscape fabric, cover it with 1 to 2 inches of shredded bark. Pull the mulch 6 inches away from the plant stems. Maintain even soil moisture until the plants resume vigorous growth -- usually in one to two growing seasons. Pull weeds as they appear and replace mulch as needed.
Prevent weeds by laying down a water-permeable landscape fabric. Overlap the edges by a few inches and anchor the fabric to the ground with wire or plastic pegs made for the job. Fabric is best used with shrubs, but not perennials with a creeping habit. To plant, make two crossing cuts in the fabric with a sharp knife, pull up the flaps, and plant through the opening.
Speed plant growth by scattering granular fertilizer or composted manure over the planting site. Choose a fertilizer formulated for your plants and follow directions carefully.
Photography by Sabin Gratz/National Gardening Association