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Pruning ornamental trees and shrubs

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Shaggy hydrangea (Hydrangea heteromalla 'Bretschsneideri')
Photo: Jardin botanique de Montréal (Gilles Murray)
Hydrangea heteromalla 'Bretschsneideri'

We are fortunate to have trees and shrubs around us. They are not only attractive, but they also purify the air, serve as windbreaks in winter and offer shade in summer, act as visual and sound screens, provide shelter for birds and animals, and more. They are a long-term investment and as such deserve careful maintenance.

This section covers the basics of pruning trees and shrubs (other than fruit trees and roses, which require special care). It takes time and practice to learn the art of pruning. Remember that improper pruning can often be more harmful than no pruning at all. So read the pointers outlined here before getting out your shears! If you are in any doubt, it’s best to call in an expert.

Why prune trees and shrubs?

Pruning is usually done in order to keep trees and shrubs healthy and for safety and security reasons. However, there are a number of other reasons for pruning:

  • to better balance the tree or shrub, while maintaining its natural shape;
  • to encourage flowering and fruit production;
  • to encourage bushier growth;
  • to better display the branches or decorative foliage;
  • to clear paths or other areas around the house, fences, streets, sheds, etc.

Pruning should not be done to stunt a plant’s growth. When choosing a tree or shrub, you should consider its size when fully grown.

Recommendations

No matter what size of pruning job you are tackling, play it safe and use the right tools.

  • Always wear safety goggles to protect your eyes from flying bark, branches and sawdust.
  • Always wear leather or thick canvas gloves to protect your hands from cuts or scrapes.
  • Use well-sharpened tools. This will simplify the job and help avoid accidents. Moreover, a clean cut with no jagged edges will help the tree or shrub heal properly.
  • Disinfect tool blades with 70% isopropyl alcohol (rubbing alcohol) after pruning each plant to avoid transferring any possible diseases from one plant to another. If you suspect any insect pests or diseases, disinfect tool blades after each cut to avoid transferring the problem to another part of the plant.

Important

Never start any pruning job if you, your tools or any part of a tree are within three metres of a hydro line. Only Hydro-Québec and professional tree trimmers authorized by Hydro-Québec are allowed to do such work. For further information, visit their website or contact the Customer Services unit at 1 888 385-7252.

 

A hand secateur or pruner

It is the ideal tool for precision work and for pruning small branches less than 2 cm thick. There are right- and left-handed models.

A long-handled pruner or lopper

It will give you better leverage for pruning or cutting through branches up to 4 cm thick. It is also useful for getting at branches that would be hard to reach with a hand pruner, like those in the centre of a shrub.

A long-arm pruner or pole pruner

It is just that, a pruner on a pole. It is useful for reaching high branches or thinning the crown of a tree without a ladder. It can cut through branches up to 4 cm thick.

Pruning saw

It comes in different models and has different sizes of teeth. The finer the teeth, the smoother the cut.

Hand shears

They are used for shaping new growth on a hedge or shrub, while the wood is still soft. They are also useful for trimming grass and twigs.

Anvil-type pruner

If you are using an anvil-type tool, place the blade against the part of the branch to be saved. That way you will avoid crushing the branch tissue and promote better healing.

Keep all your tools clean and sharp. Get in the habit of cleaning them after each use. Sharpen and oil them before storing them for the winter. This will make them easier to handle and they will last longer.