Diseased and dangerous trees
Narrow definitions of tree surgery explicitly mention the treatment of diseased trees. Taking this definition, there is no best time of year for tree surgery. The sooner you remove the diseased limb or section of tree, the better for the health of the tree.
Likewise, if you have large, dead or dying branches leaning over your house, or a footpath or road, this needs urgent attention. Waiting until winter because ‘the tree needs all its nutrients back’ should not come into the equation.
So, prioritise the safety of people first, then look at what the tree needs to thrive.
Why the best time of year for tree surgery is often winter
When it comes to general pruning, many sources will confirm that the best time of year for tree surgery is in the winter, but this needs some qualification.
There are several reasons why winter is usually the ideal time for heavy pruning.
First, the tree is usually in its dormant stage. It is neither sending sap to the leaves for photosynthesis, or withdrawing nutrients to fuel itself during the winter.
Why does this matter?
Heavy pruning in the spring will lead to sticky wounds that are a magnet to pests and microbes that carry disease. In autumn, many trees are gathering back nutrients to survive the winter. That’s why the leaves drop off. If you prune before this has happened, you will be depleting the tree’s winter reserves. This survival stress can mean your tree becomes vulnerable to disease.
You can avoid both of these scenarios by pruning in either the winter or summer months. However, there are two issues with significant pruning in the summer. First, heavy pruning is a traumatic process and will limit the growth of fruit and flowers as the tree recovers. Now, if you have an overexcited tree, you might prefer to prune it in the summer to help tame it.
The other main reason for avoiding summer pruning is that it’s harder to see the overall shape of the tree when it is in full bloom. It is also easier to miss branches that are growing at strange angles when they are covered with foliage.
When the best time of year for tree surgery may not be winter
Before you settle on winter tree surgery, it is important to know that there are many valid reasons why some people decide to prune their trees in spring, summer or autumn.
This mainly boils down to how individual tree species react to pruning.
For example, trees of the genus Prunus, including the cherry, use their sap to protect their wounds from infection. Therefore, it makes sense to prune cherries and their relatives in the spring or early summer, when sap is rising.
Other exceptions to the winter pruning ‘rule’ are the genus Acer (including maple) and birch. These trees release a lot of sap when pruned, regardless of the season. If your trees have been planted mainly for aesthetic reasons, you may prefer to prune these species of tree in the summer, when the leaves can hide the messy evidence.
It is also best to avoid heavy pruning if your trees have already had to deal with seasonal weather extremes. For example, you might want to wait a few weeks following an extended frosty spell. This will give your trees the time they need to recover.
Getting an expert opinion
For qualified advice about when to time your tree surgery, get in touch with Arborcure. We can give you specific pruning advice that fits your specific trees and your overall aims for your garden or plot of land.