Ornamental boxwood shrubs are generally used to create barriers along walkways, pathways and similar fixtures in a landscape, and their box shape and evergreen leaves make them easy to pick out among other plants. Pruning these shrubs is key to keeping their size and shape under control, but pruning should be done carefully to avoid damaging the plant. In general, the boxwood does not require or adapt well to severe pruning, such as removing a few feet of foliage at a time.
Reasons for Severe Pruning
Such severe pruning as removing 2 to 3 feet of foliage from a boxwood should only be done in emergency situations. For example, extreme damage from winter cold or strong winds may break branches and necessitate the removal of a lot of outer foliage. Similarly, one of the first steps to treat diseases such as mold infections, or severe insect infestations, is to prune away dead, damaged and infected areas of the shrub. This may require you to remove a few feet from the ends of the shrubs. Finally, severe pruning may be an option if your boxwood is growing out of control.
When to Severely Prune
The best way to help your boxwood plants survive a severe pruning is to time it correctly. Severe pruning should be done in later winter or early spring, generally between January and March. If possible, remove only a foot a season, spreading your severe pruning out over a number of years to lead to faster recovery. You must conduct severe pruning before any new growth begins for the year. At this time, the plant is still dormant, meaning that little nutrition and water are flowing through the growth. Pruning at this time cuts back on the amount of “bleeding” from the wounds. It also allows for healthy and full growth in the following growing season, since there will be new, clean areas from which the boxwood can sprout healthy growth.
Recovering from Severe Pruning
Your boxwood will survive a severe pruning session, but it might not look like it at first. The boxwood grows most of its foliage on the outside; the interior of the plant is often bare or features only old and wilted growth. If you remove most of the outer foliage, you will be left with a dead-looking shrub. Maintain proper feeding, watering, mulching and light exposure for boxwoods in your area to help the shrub recover faster. More than likely, the shrub will take at least two seasons to return to normal, fully filled out growth patterns.
Regular pruning maintenance can cut back on the need for severe pruning. This pruning should also be done in early spring. Remove the tips of last year's growth, as well as any areas of the bush that were damaged by the winter weather. This encourages new, healthy growth in the spring, and also allows you to control the size and shape of the tree.