Woody plants are actively building up their storage of sugars as they approach leaf drop. Pruning in the fall limits this process and reduces the amount of energy the plants have available through dormancy. Also, pruning now may encourage woody stems to
send out new growth that will be more susceptible to freeze damage during winter.
With the exception of removing dead or diseased branches, it is best to save pruning until after winter. For shrubs that bloom in spring, pruning in the fall can reduce flowering. Spring-flowering shrubs, such as forsythia, lilac, flowering quince, almond, beautybush, deutzia, pyracantha, mock orange, cotoneaster, weigela, viburnum and witch hazel should be pruned after they bloom.
Summer-blooming shrubs, such as hydrangea, rose of Sharon, butterfly bush and crepe
myrtle, can be pruned in early spring because the blooms establish on new growth. With
a few exceptions, most deciduous trees respond best to late winter/early spring pruning.
Proper timing of pruning allows trees to go into dormancy healthy, without increased
stress from pruning.
