Cold damage can turn boxwood foliage brown, bronze

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I see a lot of brown to bronze foliage on some of my boxwoods. Because they are supposed to be evergreen, is something wrong with them? -- Charles

A: It's probably cold damage to your plants, which shows up on American and English boxwoods as bronzing of the foliage.

Plants with this condition are usually in an eastern or southern exposure. They get full winter morning or afternoon sun, which on a bright winter's day, when combined with fluctuating high and low temperatures, can cause rapid change in leaf tissue and the change in leaf color.

Japanese boxwoods in the same exposure may show foliage burn on the upper part of the plants. In some cases, the foliage usually turns almost white in color, and within a few days is crisp dry and dead. This foliage is easily pruned with no ill effects. The same thing occurs to new foliage that came out late the previous growing season. This growth has not developed enough hardiness to resist frost or extremely low temperatures.

Another problem you can see on boxwoods is a yellow leaf margin. This indicates that the plant is suffering a nutrient deficiency or a nematode infestation in the root system.

Boxwoods need calcium, nitrogen, phosphorous, and potassium. If you suspect a nutrition deficiency, get your soil tested.

As with other ornamentals, boxwoods respond best to split applications of fertilizer. The first should be made in mid-March, the second in mid-May, and the final application in July. If you use a slow release fertilizer, two applications (March and July) should be sufficient.

Use a complete fertilizer. A good rule of thumb is to use one tablespoon of fertilizer per foot of plant height. Scatter the fertilizer over the mulch around the drip line of the plants. You do not have to move the mulch. Do not ring or band the fertilizer.

Die-back is another common problem in boxwoods. It's characterized by a sudden dying of stems and branches within the plant. About the only solution is to prune the dead stem as soon as it is seen, and then spray immediately with a fungicide.

Annual pruning on most plants is necessary to keep them in bounds and in the desired shape. However, pruning should be limited to removing twigs or small branches that are distracting from the shape of the plant.

Aerating the lawn

It's good to aerate your lawn, but winter is not the time to do it.

Aeration relieves soil compaction, allowing the roots to grow better and deeper, and allowing more air, water and nutrients to reach the roots.

Grass is dormant in winter, though, and the roots are not growing, so there is very little, if any, benefit to early season aeration.

Warm season grass roots don't begin growing until the soil temperature stabilizes above 65 degrees, which occurs about April 15 in the Augusta area.

It's actually best to wait until complete green-up before aerating, which usually occurs about May 1. The best time to aerate is May or June.

Sid Mullis is the Director of the University of Georgia Extension Service Office in Richmond County. Reach him at (706) 821-2349 or smullis@uga.edu.


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