Late winter is a great time to prune, because the trees and shrubs are still dormant and you can clearly see the structure of the branches.
Late Winter Pruning
Sometime in the late winter, we get a chance to wander around the garden – albeit that some will still be in galoshes. This is a great time to assess the health and state of your shrubs and to think about late winter pruning. The individual branches and internal structure of deciduous shrubs is much easier to see in winter, than it is when leaves and blooms cover the shrub. There are several basic steps to pruning shrubs.
All these problems will be apparent in late winter and can be corrected without tangling with excess growth in spring or summer. Late winter pruning should be completed before the new growth cycle begins, but not when very cold weather is still around. This will vary from late January in the south to possibly as late as March or even April in the northern states. Whenever you choose to do late winter pruning, it will be one of the first gardening jobs of the year, and generally a very welcome one