Why is Winter Pruning important? What benefit does it have?
Winter Pruning (sometimes called Rejuvenation Pruning) will actually help bring the natural shape of the plant back, as well as help with disease issues. Ornamental trees and shrubs with with dense canopies can have more disease issues due to the fact that there is any air flow through the tree. Better air flow through the plant means fungus and insects are less likely to turn the plant into a home.
Winter Pruning (Rejuvenation Pruning), also helps to make the plant stronger by removing the older, less healthy branches. The over structure of the plant is improved by winter pruning. Since the leaves have dropped, it is much easier to see crossing and diseased branches.
Why not do this during the growing season?
The plant is dormant, or shut down, in the winter months. Winter Pruning allows the customer the ability to take more off and it is FAR less stress on the plant. During the growing season pruning should be limited to slight shaping and minor ‘control’. Removing anything more than 15%-20% of the canopy can cause undue stress to the plant.
Some plants (such as Oak trees) can only be pruned in the winter months. When the plant is pruned, an open wound is caused by this action. This wound could invite insects. Some trees (such as Maple Trees), if pruned at the wrong time of the season will produce more sap at the wound, and will not be able to transport the nutrients the tree needs as well as it could have.
Having a landscape professional, who knows the trees and shrubs, will be able to help you out and give you recommendations on how best to handle each plant. The landscape professional preforming this pruning, can actually help improve the overall health of the plant.