Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, November 21, 1993 TAG: 9311220296
SECTION: HOMES PAGE: E-1 EDITION: METRO
SOURCE: John Arbogast
DATELINE: LENGTH: Long
Here are some suggestions from the Virginia Nurserymen's Association regarding how effectively plants can be used - with proper placement and selection, of course - to block or reduce noises.
The first work with screens of living plants for noise reduction was done in Germany to decrease the noise of highways which ran through residential areas. Since then, much work has been done by state and federal highway departments in this country to develop optimal barriers.
Thus, another element of landscape design is the use of plants for engineering purposes. Acoustical engineers know that lining a room with spongy wall boards or thick draperies can reduce drastically the sound level within it. The loose fibers absorb and deaden sound that otherwise would be reflected and increased by reverberations from solid surfaces.
In the outdoors, a similar beneficial effect is given by the many surfaces of stems and foliage of trees and shrubs. Even grass contributes to this noise abatement on a smaller scale.
If this reminds you that your landscape plan should use plants for this purpose, consider that evergreen conifer trees perform this engineering function somewhat better than deciduous varieties because the needles work as sound screens all year.
Q: When is the best time of year to start trimming young barberry bushes into a hedge? Also, what type of fertilizer should I use for them and when? B.W., Hillsville
A: Early spring, just as the plant's new growth is coming out, would be the best time to begin training barberries to become a hedge. At that time, cut back the height of the barberries to stimulate lateral or side shoot development.
If the barberries already have grown taller than the height you want the hedge to be, prune them to several inches below the desired hedge height to allow room for regrowth.
Also, part of that same early spring training will be to trim the outer sides of the barberries but not the sides facing adjacent plants. Taper the sides by holding your clippers at an angle so that the lowest branches will stick out further than the top branches.
This early spring trimming likely will stimulate growth, so plan on doing a second shaping in late spring or early summer. At that time, the location of clipping should be a few inches farther out than the early shaping so that some of the spring's growth can be left on the plants.
Generally, barberry plants growing in average soil will not need fertilizer. However, if the growth appearing on the stems in early spring seems to be weak - little stem elongation and small, anemic-looking leaves - the plants may be helped with a mid-spring application of 10-10-10 scattered lightly around each plant and scratched into the soil or mulch with a rake and watered in well. If you have a small number of barberries to fertilize in mid-spring, the other possible method would be to give each plant a soaking with a soluble (kind that is mixed in water) fertilizer prepared according to package directions instead of using 10-10-10.
Q: I recently moved into a home with three large black walnut trees (10-30 feet high and about 12 inches in diameter). I want to remove the trees because it is my understanding that perennial beds, ornamentals and a vegetable garden will not grow in the vicinity of such trees.
If I have the trees cut off at ground level, how long must I wait until I can safely plant these things? Also, I have three Kousa dogwoods (1-3 years old) in containers. Can they stay in containers over winter? If so, please give any tips to insure their survival as they are some of the plants I eventually would like to use to replace the black walnuts. J.W.W., Blacksburg
A: It is my understanding that it takes at least two years after a black walnut is cut down before susceptible plants can be grown without some injury in soil adjacent to the walnut roots.
Yes, those Kousa dogwoods can over-winter in the containers. To prevent death of the roots, which can occur if they reach a temperature in the low 20s, bury the pots as soon as possible, almost up to the rims in a well-drained garden spot where the soil is fairly loose. This way, the young plants will be able to go through dormancy, but the roots will be insulated by garden soil around the pots.
Remove the pots from their over-wintering garden spot next spring after danger of hard freezes is over. Once growth comes out on the Kousa dogwoods they will need to be watered, like any other potted plant, when the soil is almost dry to the touch a couple of inches under the soil surface.
If you plan to keep the Kousa dogwoods as container plants for a while, talk to a nursery for advice on how to professionally maintain container stock.
Send short questions about your lawn, garden, plants or insects to Dear John, c/o the Roanoke Times & World-News, P. O. Box 2491, Roanoke 24010-2491. We need your mail, but this column can't reply to all letters. Those of wide appeal will be answered each week. Personal replies cannot be given. Please don't send stamps, stamped envelopes, samples or pictures.
John Arbogast is the agricultural extension agent for Roanoke.
by CNB