After working with boxwood for the last 29 years, I have come to the firm conviction that much of the dying or declining of boxwood is due to faulty cultural practices, or to extremely unfavorable weather conditions," says Albert S. Beecher, Virginia Tech extension specialist, ornamental horticulture. Beecher also is president of the American Boxwood Society.
In Virginia we have several very dry years causing a deficiency of soil moisture, he says. "The failure to water boxwood properly during these stress periods has contributed to the death or decline of much of the boxwood."
Another contributing factor, Beecher says, is the lack of proper plucking, or thinning, of boxwood plants. This is especially true of English boxwood.
"Healthy boxwoods have a green center and leaves all the way up the stems. In order to obtain this condition English boxwood need annual thinning or plucking to allow light and air to reach the center of the crown. Even though the plant appears to be growing exuberantly, this thinning or plucking is needed each year.
"Another important step in the growing of healthy boxwood is to clean up the dead leaves that accumulate inside the plant close to the ground each year. If this material is not cleaned out, there will be a buildup of dead leaves. Very often aerial roots will develop in this accumulation. In stress periods these aerial roots can be easily damaged, and when this occurs, the top portion of the plant will die.
"In much of the boxwood where root rot or decline has been reported, I have observed that there has not been an active management program to keep the plant clean or properly thinned."
Here are some of Beecher's tips for taking care of boxwood:
The ideal soil for boxwood is fairly stiff clay, well-supplied with organic matter.
It is not necessary to fertilize boxwood every year. Its requirements will vary depending on the type of boxwood, soil and growing conditions. Fertilizer will not correct bad physical condition in soil.
Boxwood will tolerate shade but will have stronger growth where there is sunlight for at least part of the day.
Transplanting can be done anytime except when the plants are in active growth or the ground is frozen or too wet.
Boxwood plants that are too tall can be cut back several feet in early spring.
A light mulch helps maintain a more even temperature in the upper layers of soil and is helpful in preserving soil moisture. Roots may be damaged by mulching too heavily. Mulch to a depth of one inch.
Oak leaves, sawdust, peanut hulls, pine needles and wood chips are good mulching materials for boxwood.
Do not neglect to water even during the winter months if the ground becomes extremely dry.
Avoid digging around boxwood because the roots are shallow.