“Today is the day!” I say, as I inspect my loppers, hand pruner and pruning saw. For tree care professionals and many homeowners, winter is pruning season for deciduous trees and shrubs, with much of it occurring in February and March before leaves emerge.
There are many advantages to pruning in the winter. My favorite reason? Leaves are heavy. A large branch devoid of leaves is easier on the back. The more important reasons for pruning in the winter involve plant health.
Strategic cuts
A tree naked of leaves reveals the underlying branching structure. Before pruning, plan out the cuts. While woody plants tolerate pruning, it can be overdone.
The goal is to make as few cuts as possible and to keep wounds as small as possible. But, there is a balance to that. A tree will struggle to seal off one large wound as opposed to multiple smaller wounds.
In a perfect world, we would be pruning our newly planted shade trees the second year after they get planted and each year after. This proactive pruning would address small problems before they become big problems hanging over your garage.
Of course, we rarely get to play a role in the structural pruning of our young trees. Issues develop over time and are passed from one homeowner to the next.
Strategically planning your cuts can help avoid removing more than 25% of the living canopy at one time. Deadwood does not count.
Stored energy
Trees and shrubs dormant in the winter have stored energy as they await spring growth. Spring sees a surge in vegetative growth in most woody plants, which facilitates sealing where we made our pruning cuts earlier in the winter.
Certain species, like maples, also have a lot of stored sap. In the past, many folks, including Illinois Extension professionals, avoided pruning maples in the late winter, as it would often trigger sap to flow out of the wounds like a fountain.
After studying this effect, tree experts determined that pruning maples in the winter and triggering sap flow did not affect the health of the plant. So, prune away on your maples this month.
Pests and diseases
Let’s face it, pruning creates wounds on a living thing. There are certain insects and diseases that can use these wounds to infect a tree. Fortunately, there are few active pests in the winter, so open wounds have little to attract.
However, our own pruning tools can be a source of a problem. Some diseases, such as bacterial fire blight, can spread from one infected branch to an entire tree canopy by a contaminated saw.
In the winter, this disease is dormant and less likely to be spread to open wounds. Sanitize pruning tools between cuts using rubbing alcohol, especially on trees with suspected disease.
When to call an arborist
I personally do not do tree work in my large shade trees. One bad fall and a lucky landing made me realize it is dangerous work. Now, when canopy work is needed, I call the pros. Here are tips for when you need to call a certified arborist:
- If your feet need to leave the ground to make a cut.
- If the tree is near a structure or power lines.
- To remove limbs larger than 6 inches in diameter.
- If there are major structural issues, decay or root problems.
- To address storm-damaged trees.
To find local certified arborists, check out TreesAreGood.org and search by zip code.
With pruners on my belt and loppers in my hand, I head outside, only to be met by a howling February wind that quickly subdues my motivation. After retreating to the warmth of my home, I decide, like the proverbial groundhog, that today is not the day for pruning. Let’s give it another try after a few more weeks of winter.
For more gardening tips, go to extension.illinois.edu.
