Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: SUNDAY, April 16, 1995                   TAG: 9504180046
SECTION: HOMES                    PAGE: C1   EDITION: METRO 
SOURCE: JOHN ARBOGAST
DATELINE:                                 LENGTH: Medium

TO FERTILIZE OR NOT TO FERTILIZE TREES - THAT IS THE QUESTION

Landscape plant fertilization is not a "cure-all" for all cases of poor growth, nor is it something that needs to be done for established plants every year. Keep in mind that applying more fertilizer than a plant needs not only wastes fertilizer and time, but it can result in ground-water contamination as excess fertilizer runs off or leaches through the ground.

Here are some reasons gardeners might need to fertilize landscape trees and shrubs:

Age of plant: Newly transplanted and young trees and shrubs should be moderately fertilized annually for the first two or three years.

Very old or neglected specimens often require nutrients.

Soil test results: Analysis of the soil should give an idea of nutrients already present.

Visual inspection of the plants: Look for signs in the new growth or recall last year's appearance. Signs that a plant might need nutrients include poor or yellowy leaf or needle color; reduced leaf size from normal; premature autumn coloration and leaf drop last fall; reduced twig and branch elongation and retention last year; and overall reduced plant growth and vigor.

Remember that stresses on landscape plants, which would include insects, diseases, weeds, soil compaction, improper chemical use and adverse weather, can either cause symptoms similar to nutrient deficiencies or contribute to the inability of a given plant to take up nutrients.

Nutrients are commonly applied as: granules, such as 10-10-10; plant fertilizers sold for specific crops such as azaleas, roses or trees; plastic coated slow-release granules; water mixables, such as Miracle-Gro or Peter's; foliage feeding formulations; slow-release compressed briquettes designed for new planting projects; and fertilizer spikes, which are compressed forms of fertilizers designed to be pounded into the ground for subsurface fertilization.

Folks with limited time should be pleased to know that the easiest and most inexpensive way to fertilize trees and shrubs effectively is to simply scatter the proper amount of a fertilizer on the soil surface or over the grass (for landscape plants surrounded by turf).

Q: I would like to know what kind of shrubs and trees like what kind of mulch. I'm thinking of plants such as rhododendron, flowers, bulbs and boxwoods; and mulches such as pine tags and pine bark. Mrs. P.W.K., Galax

A: I do not know of any research that shows that certain plants do better with any particular organic mulches. In most cases you should use the organic mulch that is available, attractive and fairly coarse.

The "organic mulch rules" are important. It's believed that gardeners should use no more than a 21/2-inch thickness of organic mulch, do not pile up mulch against the trunk bark, be sure that the mulch is aged but has not been in the middle of a large pile for so long that it has a very strong odor, and use only a small amount of mulch over poorly drained soil.

As a recent condominium fire in Salem illustrated, it's wise to avoid mulches that are very dry, such as pine needles, in areas where smoking is allowed.

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.