With the exception of removing dead or diseased branches and “light” pruning, it is best to save this garden task for next year. Pruning is considered “light” if 10% or less of the plant is removed. For shrubs that bloom in spring, even light pruning in the fall can reduce flowering. It is best to prune spring-flowering shrubs, such as forsythia, lilac, flowering quince, almond, beautybush, deutzia, pyracantha, mock orange, cotoneaster, weigela, viburnum and witchhazel 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 are set on the new growth. With a few exceptions, most deciduous trees respond best to late winter/early spring pruning. This practice allows gardeners a better view of the cuts since the trees are dormant and it allows the trees to enter dormancy healthy, without the increased stressed from pruning. (Cynthia Domenghini)