When planted under trees, ground covers reduce the possibility of mower damage to the base of the tree. Some ground covers may be used to protect the roots of shallow-rooted trees. They shade the soil and keep it from drying out rapidly. Some ground covers don't require as much moisture and nutrients as grass. Therefore, they are in less competition with trees and shrubs.

Selection

Selection of a suitable plant for ground cover depends on the area where it will be grown. Some ground cover plants prefer partial shade; others thrive in deep shade or full sun; and a few grow well in either sun or shade. The selected ground cover plants listed here grow well in a wide variety of soil types. Some, however, prefer moist soil, while others need dry or well-drained soil. All the ground covers discussed are reliably cold hardy throughout Virginia. First, select types best suited to the conditions existing where the ground cover is needed. From these selected types, choose one that ornamentally blends best with surrounding plantings.

Establishment

Bed preparation: If you need to add a soil amendment, such as organic matter or fertilizer, add it to the entire planting bed, not just to 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 ten 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 usage. 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.

In open sites: A well-prepared planting bed is necessary to develop a dense, healthy ground cover planting. 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.

In sites under trees: 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 any time during the growing season, but either spring or fall is preferred. The arrangement and spacing of plants in the planting bed depends on the growth characteristics of the plant. Space plants so they will develop a uniformly covered area in a relatively short period of 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 can purchase and how quickly a complete cover is wanted. Spacing from 6 inches to 2 feet are most frequently used. The following 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 the new ground cover planting. Water during dry periods. An occasional thorough soil soaking is better than frequent light watering. 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.

Authors: Diane Relf, Extension Specialist, Environmental Horticulture and Bonnie Appleton, Extension Specialist, Nursery Crops, Virginia Tech

Publication Number 426-609, posted July 2000