Deciduous tree pruning

Here are a few guidelines to follow when pruning deciduous trees.  The tools needed to properly prune trees are a pair of sharp bypass pruners, a pair of loppers for thicker branches, and a pruning saw for larger branches. Tools should be sharp to prevent ragged cuts.

The ideal time to prune trees is in late winter when trees are dormant, before buds begin swelling in the spring. This is particularly important for trees which are prone to attack from insects and disease such as elm, ash, oak and fruit trees. Generally speaking, November to March are the safe pruning months for disease-prone trees. Dead branches can be removed in any season. Trees which run sap in the spring, such as maples, are better pruned in late winter, or after June 1st. Pruning trees in the fall can stimulate new growth which will not have time to harden off before winter and may result in winter die back.  Trees which flower early in spring, such as magnolias, can be pruned after flowering.

When pruning, branches should be cut just beyond the natural swelling at the base of the branch (see graphic). Never cut into this swollen area, as such cuts will prevent the wound from healing properly. Equally important, never leave a stub, as this can later be an entry point for disease. For larger branches a three part cut (see graphic) will prevent a heavy branch from ripping the bark further down the tree and will also prevent injury to the person pruning.  If you are pruning two V-shaped branches, never cut into the raised bark ridge which runs between the two branches. Branches larger than 13 cm in diameter should not be removed at the main trunk, but rather cut back further up the branch where the diameter is smaller. Cuts over 13 cm in diameter run the risk of never healing over properly.

Ideal targets for removal are crossing or rubbing branches, closely spaced branches, and suckers. An ideally pruned tree will have branches spaced around the tree similar to the steps on a spiral staircase. This goal is much more achievable with young trees where pruning begins the year following the planting. As a rule of thumb, never remove more than 20% of the foliage mass of the tree in one season, otherwise the tree will experience undue stress and have difficulty recovering. Do not put tar or any kind of sealer over the cuts, as studies have shown that disease can begin under such products.  

If the tree is large and upper branches are too high up, don’t hesitate to call in an expert to do the job.  Tree pruning companies with trained arborists on staff are preferred, to prevent damage to your trees as a result of improper pruning practises.

Submitted by Elizabeth Spedaliere