Often people ask us what time of year is best for tree pruning. If you’re reading this, chances are you care about tree preservation and own or have trees to manage. I’ll share some of my insights as a field Arborist in the greater Toronto area with over 20 years of experience and guide you in making the best decision for healthy trees. You’ll see that for the most part, trimming your trees can be safely and effectively done at any time of the year, no matter the species or even climate, as long as the pruning dosage is light. You can glance through the key take away boxes to digest the information fast.

Safety is the most important aspect of urban tree maintenance. If you notice any weak or damaged limbs in your tree, get it taken care of right away. For example, if there is a large crack in a tree limb where people are frequently walking underneath, don’t wait for the perfect time of year to have it taken care of, have it looked after as soon as possible.

Dead and diseased branches can also be pruned from the tree at any time of the year no matter what the species without any negative effects to the tree.

Key Take Away

Safety is top priority, prune as required.
Dead and diseased branches can be cut at any time of the year.

The vast majority of pruning service calls we perform can be accomplished with a light pruning dosage which is considered light when less than 10% of living branches are removed from the tree. This can safely be done at any time of the year with little regard to climate. The idea is not to create stress for your tree.

Key Take Away

Pruning less than 10% of existing canopy is considered light and can generally be safely done at any time of the year.

There is a general consensus in the Aboricultural community that dormant season is the best time to have your trees trimmed. The primary reason being that pathogens and insects, transmitters of tree diseases, are less active. I do agree with this approach if you have a vulnerable tree. For example Oak Wilt is a disease that specifically affects Oak trees, particularly Red Oaks, and is spread through burrowing insects. Fresh pruning wounds can attract insects, so it is best practice to prune a Red Oak tree in the dormant season.

Key Take Away

Trees vulnerable to pathogens spread through insects should be pruned in the dormant season.

If you have flowering trees and want to maximize flower production, the time of year you trim will have an effect on bloom.

Trees that bloom on last years growth also referred to as early bloomers, should be pruned after blooming. This will ensure a good flower yield for the current season and leaves enough growing time before dormancy to stimulate new growth for the following season.

Trees that bloom on current years growth, also known as late bloomers, can be pruned early Spring to stimulate increased growth nodes for more flower production in the current blooming season.

Key Take Away

To maximize flower production, prune early bloomers after current seasons bloom and late bloomers in Spring before current seasons bloom.

Final Thoughts

Trees above all should be pruned in accordance to good Arboricultural practice, and this in my opinion is far more important than the time of year you decide to prune. Ask your Arborist what exactly will be done to your tree and how will it benefit from being pruned.