|Winter pruning at Riverside Boat Club, Memorial Drive, Cambridge|
In winter trees enter their dormant phase. They are "resting" and little to no growth takes place. During this time traumatic effects of pruning are less likely to negatively impact your trees and shrubs. Sap loss is kept to a minimum while fungus and other bacteria - who may also be in a dormant phase - are less likely to attack the open wound on a pruned branch. Without leaves on the branches you will have a better concept of overall tree shape. The lack of leaves aids in exposing all branches increasing your ability to identify dead, weak, or congested branch areas.
Dead branches (branches with no leaves or buds and many times fungus growth and flaking bark) are the exception to winter or dormancy period pruning. Dead branches can, and should, be removed any time of year for arbor health and public safety.
The Conservancy Volunteer program does the majority of pruning in late fall, winter, and early spring. The linked website in this post is an excellent model to follow when pruning trees. http://www.tree-pruning.com/index.html
Get outside, enjoy the refreshing winter air, and help your trees and shrubs by pruning today!