Spring Snow Crab

When Should I Prune My Tree in Calgary

Spring is upon us and the requests for tree pruning are rolling in. It is not uncommon to hear customers ask: “When should I prune my tree in Calgary?” In my usual fashion, the answer is – it depends…

There is an expression that many arborists like to quip when asked about when trees should be pruned: “Prune trees when the saws are sharp!” but there is a bit more to it than that. In this post I am going to run you through some considerations about when you should have your trees pruned. Some of the most important factors include time of year, environmental conditions, tree age/health, tree species, and objectives.

Seasonality for Tree Pruning in Calgary

Many pruning/maintenance activities can be performed any time of the year, but there are some guidelines to follow that are based on the tree phenology and pruning objectives. 


Some things that we generally prune for anytime of the year are:

  • Dead, dying or diseased branches.
  • Clearance issues such as branches interfering with utility lines, rubbing on buildings, or obscuring signs.
  • Storm Damage – sometimes we need to remove branches that have been broken or damaged in a storm.
  • Tree risk mitigation – if a dangerous situation is identified it is best to deal with it immediately. 

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Winter can be an excellent time to prune trees as trees are dormant and disease pressure is considerably lower. Things to consider when winter pruning trees:

  • Tree leaves are gone so it is much easier to prune for structure, shape, and disease removal. 
  • Trees are dormant – this can minimize pruning stress as most trees aren’t actively photosynthesizing.
  • Large pruning cuts have the potential to crack due to cold stress, so we try to avoid this type of pruning work if the risk of extremely low temperatures exists.
  • Dead wood identification can be harder without leaves – but we have ways to determine if a branch is dead.
  • Elm Trees ***See note below.


Spring seems to be what kicks off the tree-work season and can be a good time to prune trees depending on pruning goals.

  • Trees should be pruned after bloom to maximize flower and fruit production
  • If the objective is to limit growth, reduce fruit, or keep a tree contained due to space limitations this can be a good time to accomplish those goals.
  • Disease spread can be an issue due to wet weather and this should be considered.
  • One should also be mindful that in the spring, tree sap is readily flowing and trees that tend to ‘bleed’ sap (such as birch, poplars, and maples) should not be pruned or minimally pruned at this time. 


The glorious summer season is usually short and sweet in Calgary. The days are long and the sun is hot, which does pose some challenges for both people and trees. Summer heat and drought can stress trees and inappropriate summer pruning can increase stress. Some things to consider when pruning trees in the summer are:

  • Minimize how much is removed to prevent sunscald or scorch.
  • If conditions are droughty minimizing or pruning later in the year is advised 
  • Remember, trees are busy photosynthesising and are trying to make the most of our short summers. Removing too many leaves (by over pruning) reduces a tree’s ability to create and store energy for future use.


The arrival of fall signals the end of the growing season for most plants (trees included) and this can be an excellent time to prune trees. A few things to consider are:

  • Careful not to cut off last minute energy reserves the tree may have
  • This is a good time to prune trees that ‘bleed sap’ as sap flow is greatly reduced. 
  • Avoid large pruning cuts as they won’t have time to seal and will be exposed all winter.
  • Elm Trees ***See note below.

Closing Thoughts on When to Prune my Trees in Calgary

A lot of our discussion has focused on when to prune trees in Calgary based on seasonality, but I wanted to mention that both tree health and age should be considered. As trees age or if their health is questionable, they will have a lower tolerance for pruning. To maximize pruning benefits for both trees and people, veteran trees and trees in poor/declining health should be pruned when they are dormant.

***Note: Elm trees in Alberta must be pruned outside of the seasonal elm pruning ban. For more information regarding pruning elm trees go here. This is very important as Alberta is considered a Dutch Elm Disease free jurisdiction and by adhering to the elm pruning ban we are helping to ensure that we have healthy and disease free elm trees to enjoy in the future. 

If you have any questions regarding pruning your trees feel free to contact us. If you would like a free no-obligation quote, we would welcome the opportunity to stop by and see what we can do to help you accomplish your pruning objectives.

For Information on How to Select an Arborist, please see our blog post or give us a call.

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