The best time to trim most shrubs is early spring, with the exception of spring-blooming shrubs, which should not be trimmed until just after their blooms fade. Early spring pruning gives the shrub plenty of time to develop new growth during the summer season.
The best way to trim shrubs is to cut dead and damaged branches with pruning shears just above the place where the branch meets the trunk. A 45-degree angle at the cut allows water to drain off the cut area to decrease the risk of fungal growth or disease developing. Trimming shrubs lower than their optimal height allows for the development of new growth.