How to Trim a Boxwood in Winter

Trim your boxwoods in late winter, shortly before they break dormancy. Prune trees before the appearance of new leaf buds in springtime.

Disinfect your pruning shears by dipping them in a solution of diluted bleach water that contains 9 parts warm water to 1 part chlorine bleach. Use a bucket tall enough to submerge the entire length of the blades on your pruning shears.

Snip out broken and bent branches first. Remove these boxwood branches slightly above the point of damage, making your pruning cuts inside the area of healthy growth.

Remove unsightly or overgrown branches that emerge beyond the uniform shape of your boxwood shrubs. For hedges, make the tops narrower than the bottoms to protect them from breakage from excessive weight during an ice storm or period of snow accumulation. Cut back the height of your boxwood by snipping off about a third of the tallest branches, bringing them down to about 1 foot lower than the desired height. During the second year of pruning, cut back half of the remaining tall branches. Prune the remaining third during the third year of pruning.

Thin out interior portions of your boxwood shrubs to increase airflow around branches and leaves. Thin this way once a year in late winter to allow abundant amounts of light and air around branches and foliage, a practice that minimizes the risk of fungal growth and other diseases. Prune off crowded sections of foliage by cutting up to a third of the interior foliage each year. Make these pruning cuts just above the area where crowded small branches attach to larger ones.