Tree Pruning Essentials

Pruning trees has many benefits when done correctly. Pruning has been called “one of the best, worst maintenance practices” performed on trees. The process creates wounds, which have a major impact on plant processes. Improper cutting on a tree causes severe damage or even death. To prune properly, it is important to understand both the proper techniques and how the tree responds to pruning.

Early pruning and training young trees allows an arborist to promote healthy branch growth, better branch to trunk aspect ratios, develop strong structure, eliminate co-dominant stems that are often damaged in storms, redirect branch growth, and reduce maintenance later in the life of the tree.

Note: Tree branch to trunk aspect ratios, refers to the size or diameter of a branch compared to the diameter of the trunk. Ideally, the branch diameter should be less than 1/2 the trunk diameter.

Early pruning and training should begin within 2-3 years of tree establishment in the landscape. It is recommended that this training be done by or at the direction of a trained arborist. Poor pruning can cause damage that lasts the life of the tree. Proper tools facilitate making proper pruning cuts. Often all that is needed is a pruning saw, bypass hand pruners and bypass lopper.

Pruning cut location is critical to a trees growth and wound closure response. Make pruning cuts outside of the branch collar to avoid damaging the trunk or parent limb. If a branch needs to be shortened, prune back to a secondary branch or bud. Cuts made between branches or buds, leaving stubs, can lead to decay.

A good structure of well-spaced branches, along a strong central trunk, should be established when the tree is young. If the tree variety allows, establish a central leader.

Sometimes a tree will develop double leaders, called codominant stems. They can lead to structural weakness. One of them should be removed or the less dominant one shortened. Keep in mind that lower branches will be pruned away as the tree grows to provide clearance for mowers, pedestrians, and motor vehicles. They will not be permanent, but may be worth keeping a few extra years for their energy making capability. In the long run, if they eventually have to be removed, do it before they reach 2 inches in diameter.

Branches similar in size to the trunk or parent limb are more prone to failure. This is the aspect ratio. These branches are best shortened to slow their growth or removed.

Try to achieve a well-balanced branch architecture. No more than 25% of the crown should be removed in one pruning. Removing too much canopy can starve the tree. Young trees are more forgiving.

Pruning is a process – not a onetime event.

Check out this resource from Lindsey Purcell with Purdue University Extension: Tree Pruning Essentials