The last two winters were especially severe and caused damage to many boxwoods. To guard against damage this coming winter, it's important to understand why winter injury may occur and what to do to prevent or minimize it, according to Albert S. Beecher, Virginia Tech professor of landscaping and president of the American Boxwood Society.
An inadequate supply of soil moisture is often a factor in winter damage, he says. Boxwood is potentially vulnerable following a dry summer or fall. High winds during late fall or winter may cause excessive loss of moisture, and if it's not quickly replaced the plants may suffer.
If the rainfall has not been adequate, the boxwood should be watered thoroughly before the ground freezes. Light watering does no good and may be harmful. Let the hose run slowly for two or three hours so the water can soak completely into the root zone. Two or three inches of mulch will conserve moisture and prevent deep freezing of the soil. Sawdust, wood chips, compost, pine needles and similar materials can be used for mulching. A burlap screen to windward, supported by stakes in the ground, will provide wind protection. The wind would draw moisture from the plant.
Remove all fallen and diseased leaves from the center of the plant and put them in the trash can. All dead branches should be removed and burned. Remove snow from boxwood during and after a storm or as soon as practical by shaking the bush with a broom -- unless the branches are frozen, when they break easily.
To grow healthy, strong boxwood, it's usually necessary to prune them every year. The center portion must receive air and light, or it will die back and the stems will become weak. This thining can be done anytime the weather is suitable for working outdoors. Much of the poor or declining boxwood is due to failure to thin the plants over the years.
Height can be controlled by shortening the branches in the upper portion of the plant.A plant thinned properly will have green leaves all the way up the stem. Otherwise, stems will be weak and more susceptible to breakage by snow and ice.
Light pruning can be done any time of the year. Heavy pruning is best done in early spring.
Q -- Can impatiens plants be grown indoors during the winter ?
A -- They will grow nicely indoors but won't bloom unless they get very good light and humidity is at least 40 percent.
Q -- I have two Bartlett pear trees, one six years old, the other 10. They're loaded with blossoms each spring but bear no pears. What could be wrong?
A -- Pollination is the problem. Bartlett pears are slightly self-fruitful but seldom bear much fruit unless cross-pollinated with another variety. Duchess d'Angouleme is considered a good pollinator for Bartlett.
Q -- We planted six rose bushes last spring and they did beautifully this summer. What do we need to do to help them through the winter ?
A -- Roses need very little winter protection except in areas in the north where temperatures go well below zero for long periods of time. The best that can be done for them is to provide a mulch to keep the soil from freezing too deep.
"The Enchantment of Christmas," the 24th annual Christmas greens exhibition, will open Tuesday at the conservatory of the U.S. Botanic Garden, Maryland Avenue and First Street SW. All next week, there'll be demonstrations of decorating with evergreens and dried materials at 11 and 1 o'clock. The exhibition will be open free daily, from 9 to 5.
HOLIDAY HOUSE TOUR
The Garden Club of College Gardens will hold a holiday house tour next Friday from 10 to 7. The tour starts at 7 Pitt Court, Rockville, and plants and baked goods will be on sale next door, at 9 Pitt Court. For information call Jo Ann Sweeney at 762-0597 or 424-5868.