Not long ago I discussed the symptoms of boxwood leaf miners. If your boxwood leaves do not have the characteristic reddish-yellow mottling caused by the miner, what else could cause a thinning, unhealthy shrub?
Taft Eaker runs the homeowner landscape problems clinic for the Extension Service at the University of Georgia. He says that many boxwood problems can be traced to a failing root system. The roots may be getting too much water and drowning. Or they may be covered too deeply and be suffocating.
ROOTS ON LEAVES? Sometimes boxwoods exhibit small warts on the backside of the leaves. These “adventitious roots” are a physiological response by the plant to low light or high rainfall or low moisture conditions. When adventitious roots form, it is usually due to a wet (and probably compacted) site where low roots cannot get air and are under stress. Planting too deep also can cause this problem.
One way to avoid boxwood problems is to choose Korean or Japanese species. They are more suited to the southeastern climate than American or English boxwoods.