Lawn and Garden

Ground Covers

By John Jett, WVU Extension Service horticulture specialist

Generally speaking, ground covers include any material that covers the ground surface so that it cannot be seen from above and so that rain does not strike it. By this definition, grass, various types of paving, shrubs, and even trees could be called ground covers. However, here we are referring to ground covers as low (up to 18 inches), mat-forming, or trailing plants other than grasses or other plants that tolerate walking or mowing. Most ground covers are not intended to be walked upon and are severely damaged by pedestrian traffic.

Wherever paving, lawn, or cultivated beds are not desirable, ground covers can be used successfully. Newly cut banks and any slopes greater than 12 percent are best treated with ground-cover plantings. Around buildings, ground covers are superior to paving or structural controls for reducing heat, glare, noise, and dust.

When ground covers are chosen carefully and placed correctly, they greatly enhance the beauty of the landscape. In addition to their aesthetic value, they fulfill a number of other important functions:

  • Controlling erosion on slopes
  • Obstructing traffic without impeding view
  • Conserving soil moisture and, during periods of extreme heat, lowering temperatures in the soil
  • Reducing lawn maintenance
  • Filling narrow, oddly shaped areas where mowing and edging might be difficult
  • Providing vegetative growth where grass is difficult to maintain
  • Producing interesting patterns with variation in height, texture, and color

In practice, the ground covers most frequently used are plants that are easily propagated, vigorous, and hardy.

Selecting Plants

Selecting a ground cover depends on where it is to be used. Is the area flat or sloping? Is it in sun? Partial or deep shade? Also consider the soil at the site. Some ground covers prefer a moist soil rich in organic matter; others adapt to dry, sandy situations. Consider color, texture, height, and habit as well since some ground covers tend to grow rampantly. One problem that limits ground-cover use is the cost of installation since large numbers of small, individual plants are required. In addition, a well-prepared planting bed is essential for establishing plants and can be costly and time-consuming.

Culture

A well-prepared planting bed is necessary to establish ground-cover plantings. If you need to add a soil amendment such as organic matter or fertilizer, add it to the entire planting bed, not just individual planting holes. Organic materials such as leaf mold, compost, or well-rotted manure improve drainage in clay soils and improve water-holding capacity of sandy soils. Eight to 10 bushels of organic materials per 100 square feet incorporated into the bed may be necessary in very poor or heavy soils. A soil test provides the best guidance for fertilizer use. Without this information, a general rule would be to use 3 pounds of a commercial fertilizer such as 5-10-5 per 100 square feet. Fertilizer can be mixed into the soil at the same time other amendments are incorporated.

When you plant in open sites, a well-prepared planting bed is necessary to develop a dense, healthy ground cover. The soil should be worked to a depth of 6 to 8 inches. Take care to eliminate perennial weeds and grass that might compete with the ground cover during establishment. When establishing a ground cover under existing trees, choose shallow-rooted plants such as hostas. Since the majority of fibrous tree roots are found in the top 12 inches of soil, prepare the soil for planting only 2 or 3 inches deep to minimize disturbance of these roots and prevent damage to the tree. Most ground-cover plants can be planted anytime during the growing season, but either spring or fall is preferred.

The arrangement and spacing of plants in the planting bed depend on the growth characteristics of the plant. Space plants so they will develop a uniformly covered area in a relatively short time. Plant in staggered rows, not straight lines, to get faster coverage. Plants that spread rapidly may be spaced much wider than slow-spreading types. Spacing also depends on how many plants you purchase and how quickly you want a complete cover. Spacings from 6 inches to 2 feet are most frequently used. The chart shows the area that approximately 100 plants will cover when set at various distances. For example, if plants are spaced 4 inches apart, 100 plants will cover about 11 square feet.

Watering, weeding, mulching, and feeding will be the main requirements of a new ground-cover planting. Water during dry periods. An occasional thorough soil soaking is better than frequent light waterings. Occasional hand weeding with a minimum disturbance of the soil may be necessary. A 1- to 2-inch mulch layer of leaf mold, compost, or similar organic material will conserve soil moisture and reduce weed growth.

Planting Distance (Inches)  Area Covered (Square feet)
4 11
6 25
8 44
10 70
12 100
18 225
24 400
36 900
48 1600

Staggered Row Planting – Correct

staggered

Straight Row Planting – Incorrect

rows