Now, during the months of February and March, is a great time to prune trees.
Pruning while your trees are still dormant minimizes the risk of pest problems. It also allows your trees more time over the upcoming growing season to compartmentalize and close wounds.
However, proceed with caution. While it's true that correctly pruning a tree lengthens its life and increases its value in the landscape, poor pruning — especially "topping" — can lead to disease and structural problems.
Here are a few pointers to keep in mind.
Don't make flush cuts
A good rule of thumb when pruning is to cut the branch — not the branch "collar." If you're wondering what the branch collar is, it's the slight swelling under the branch where the branch joins the trunk.
Flush cuts often lead to decay, so be sure you're making your pruning cuts correctly. Also, keep your tools sharp.
The tree's leader
The leader of a tree is the central stem of the tree. You want your trees to be structurally strong — especially in the event of snow or high winds. A tree with its main stem or trunk branching into a narrow fork forms a structurally weak V-crotch, which is undesirable for the long-term.
For young trees that have been in the ground three years or longer, the main goal is to create a dominant "leader" so the tree can grow to be structurally strong. Arborists call this "structural pruning." For young trees, a very light pruning is usually all that is needed.
A good rule-of-thumb for all trees is never to remove more than 25 percent of a tree's crown. In some cases, 25 percent is too much.
One of the main pruning objectives with mature trees is to reduce potential hazards by removing the deadwood, weakly attached limbs, and broken branches. When possible, you also want to encourage side branches that form angles that are in "10 o'clock" or "2 o'clock" angles with the trunk.
In the event there has been recent construction in the area, refrain from removing any live foliage from your tree. Trees are often left stressed by construction, drought or soil compaction, and the food produced by their leaves is crucial for healthy tissue and replacement branches.
Early every spring, check trees for dead or damaged branches. If you do have dead or damaged limbs, remove them using proper pruning methods.
Don't "top" trees
Tree-topping is the indiscriminate cutting back of branches to stubs. Many people mistakenly "top" trees because they grow into utility wires or get large enough to interfere with sunlight or views. Without its protective crown of leaves and branches, a tree can't feed itself or protect its sensitive bark from damaging sun and heat. Also, each time a branch is drastically cut back to a stub, numerous long, skinny shoots grow rapidly back to replace it, requiring more maintenance down the road.
Topping weakens trees, leaves them vulnerable to insects and disease, and shortens their life span. Don't do it.
Finally, if you've never pruned before and don't have time to learn how to tackle the job correctly, hiring a certified arborist is your wisest course of action.
For more information
For more information about trees and how to properly prune them, visit: www.treesaregood.org/portals/0/docs/treecare/Pruning_MatureTrees.pdf
As a reminder, there are also many other good resources on the internet about correctly pruning trees. Have fun looking and learning so you will do right by your trees.
To find a certified arborist in your area, consult the International Society of Arboriculture (ISA) website, at www.treesaregood.org/findanarborist/findanarborist. When making a hiring decision, look for the words "Certified Arborist" or "ISA Certified" in their credentials.
Cynthia Orlando is a certified arborist and recent retiree from the Oregon Department of Forestry.