What’s the difference between trimming and pruning?
These words are synonymous for most source materials, but for us trimming applies to shrubs and pruning applies to big trees.
At what time of the year should we prune a tree?
For the majority of broad-leaved trees, pruning can be done all year long. What matters is the way to do it, not the time of year. We have never noticed any difference in the regrowth whatever the time of year pruning occurred, this over the large variety we care for at our customers for more than 25 years.
The founder of the Jardin Botanique de Montréal, Brother Marie-Victorin, never set forth pointing out a time of year where a tree can be pruned. However there are specific periods for fruit trees, especially if great fruit production is the goal: at spring, in March and April before flowering or at fall (October, November) after the leaves have fallen and before frost.
At which frequency should we prune a tree?
A proper pruning last on the average 3 to 4 years. The younger the tree, the faster its leaf mass grows back; the pruning of a 12 cm diameter Manitoba maple tree last one year. The bigger the tree, the longer it takes to grow back its initial amount of leaves. For example, the pruning of a big 2 meters diameter silver maple tree may last up to 5 or 6 years.
Why is the topping of a tree so harmful?
First of all, there is an inescapable principle that must be understood: there’s a balance between the volume of water pumped by the roots and trunk of a tree and the volume evaporated through the leaves. Consequently, a tree which loses part of its evaporating surface, either by pruning or by branch breaking, will always reproduce roughly its initial amount of leaves after a while. The renewed evaporating surface comes from new growth which the tree, once stimulated by the loss of leaves, develops by activating dormants (embryonic branches located beneath the bark) which become suckers. The main characteristic of those new shoots is that they grow faster and have a vertical trend.
So if we top a tree by removing, for example, 1/3 of its height and thus 50% of its leaves, the new shoots will be highly stimulated and will grow fast with a vertical trend, so that after a few years the tree will reach its initial height. The other big problem with topping is that there is appearance of dead wood and decay holes at the cuts location. After some time, a tree which has been topped too low becomes very vulnerable to gusts of wind and its life expectancy is considerably reduced. This way of topping trees is systematically performed in Europe.
Should we put paint on the wounds left by the cuts?
Never! We must leave the wounds in the open air to let them stay dry as much as possible. It’s a mistake to apply a coating because it retains humidity in the wound and favors the progression of decay and also it hinders the work of the stem collar which cannot cover the wound properly with new bark.
Initially it’s better not to cut branches attached directly to the main trunk of a tree. Particularly branches of wide diameter in proportion to the trunk. For example, if we remove a branch of 20 cm on a 40 cm trunk, the wound formed, even with a perfect cut to the trunk, will never close again and decay will create a hole after a while, thus the very frame of the tree will be weakened.
Is a permit required to fell a tree?
For most municipalities a permit is required to fell a tree of 10 cm diameter or more at chest height. For some cities a permit is required only for trees located in front of the house and for other municipalities a permit is required for any tree on a property (whether they are in front, beside or behind the house). No permit is required to prune trees. Please request information from your local government.
Are the roots of a tree harmful to houses foundations?
In most cases; no. The function, for the roots of a tree, is being its anchorage and fulfilling its needs in water. As there is no water in the cement of foundations, roots have no need to break through the foundations of a house. Naturally, if the foundation is already cracked, rootlets may break through the crack without emphasizing the problem. However, in case of severe drought, the roots of a tree may drain the soil standing by the foundations and change the bearing capacity of the ground; in that case the crumbling soil may cause the foundation to bulge and break. In another situation, when the trunk of a tree is leaning on or to close from a wall (5 to 10 cm), the pressure of the growing trunk may break the foundation.
As a general principle, hazard from roots remains an urban legend and still very hard to prove.
Do we have to spray trees against insects or mushrooms?
This kind of problem is external and generally doesn’t affect the survival of the tree. It is often cyclical and depends on the humidity level! On some years we may see lots of insects and mushrooms, on others there are less and then at other times only some types of trees are affected. We do not recommend chemical spraying except perhaps with biodegradable products. In several municipalities it is forbidden to use chemicals to spray trees. However, you can bring a branch with its leaves, from one of your infected trees, to a good nursery gardener who may possibly diagnose the problem and propose you solutions. Pruning modifies moisture content in the leaf mass of a tree; this is instrumental in decreasing insects and mushrooms (spots on leaves) problems.