The pruning of shrubs can be a bit more tricky, so I divide shrubs into broadleaf evergreens (excluding conifers) and flowering. Of course, there is an overlap between these two groups.
How Much?
Healthy shrubs can often take severe pruning if it isn’t done too frequently. In fact, some shrubs benefit from a “rejuvenation” pruning done every few years if they become leggy or misshapen. I find this works well on broadleaf evergreens such as boxwoods, hollies, Loropetalums, and even azaleas. Other than that, it’s advisable to not remove more than 25% of the total plant in a single pruning.
When?
For broadleaf evergreen plants whose sole purpose in the garden is the foliage (screening, etc.), most pruning should be done in the late winter (mid/late February for northern Georgia). The plants will leaf out shortly as spring approaches. A dose of fertilizer would also be of benefit at this time.
The pruning of flowering shrubs is a bit more problematic. Blooming shrubs produce flowers either on the current season’s growth (shrub roses, gardenias, crape myrtles, and some hydrangeas, etc.) or on the previous season’s growth (azaleas, climbing roses, camellias, forsythia, and other hydrangeas, etc.). If you prune at the wrong time, you can either delay or destroy the next season’s blooming cycle. As a general rule, if a shrub blooms before June 1, it more than likely blooms on the previous season’s growth. After June 1 is a good indicator of blooming on the current season’s growth, but there can be some exceptions. When in doubt, prune just as the bloom is finishing.
