Proper pruning is one of the most important things you can do to keep your trees healthy.
Pruning can provide the following benefits:
- remove dead, diseased, or infected branches.
- improve tree structure by controlling size and shape.
- enhance tree vigor
- maintain safety by removing low-hanging or damaged branches.
When you prune, each cut you make has the potential to change your tree’s growth or to damage it, so never make a cut without having a good reason to do so. Pruning should always be performed sparingly, because overpruning keeps the tree from gathering enough sunlight through its leaves to survive.
Pruning mature trees can demand special equipment, training, and experience. If the pruning work requires climbing, the use of a chain or hand saw, or the removal of large limbs, you should protect your ears and wear protective eye wear. For these projects, you may want to consider hiring a professional arborist or landscape company.
- Hand pruners are used for branches 1/4 to 1/2 inch in diameter.
- Loppers are used for cuts more than 1/2 inch in diameter.
- Pruning saws are used to remove larger limbs.
Note: Do not use fine-toothed carpenters’ saws. Hedge shears are of no use in pruning trees unless a formal hedge or screen is desired.
When to Prune
- Flowering Trees:
Ornamental trees that flower before June 1 should be pruned immediately after flowering. These include redbuds, smoke trees, magnolias, flowering and kousa dogwoods, hawthorns, crabapples, flowering cherries, peaches, pears, and plums.
Trees that flower after June first should be pruned in winter or spring before new growth begins. These include goldenrain trees, sourwoods, and other late-flowering trees.
- Shade Trees:
Trees restore themselves more rapidly if they are pruned in early spring before they leaf out. When the framework is bare, you can easily see which branches need to be removed. When pruning is done in early spring, the plants are soon in full leaf and actively photosynthesizing, thus providing food and energy required for closing or sealing wounds after pruning.
Some trees, such as birch, yellowwood, elm, pine, spruce, fir, and maple, will bleed excessively if pruned in the spring. Bleeding, or loss of sap, will not harm the tree, but may be unsightly or messy around the home. Bleeding may be reduced by pruning such trees when they are in full leaf (June).
How to Prune: Some guidelines from the National Arbor Day Foundation
- Never remove more than 1/4 of a tree’s crown in a season.
- Where possible, try to encourage side branches that form angles that are 1/3 off vertical (10 o’clock or 2 o’clock positions).
- For most species, the tree should have a single trunk.
- Ideally, main side branches should be at least 1/3 smaller than the diameter of the trunk.
- f removal of a main branch is necessary, cut it back to where it is attached to another large branch or the trunk. Do not truncate or leave a stub.
- For most deciduous (broadleaf) trees, don’t prune up from the bottom any more than 1/3 of the tree’s total height.
- A. Make a partial cut from beneath.
- B. Make a second cut from above several inches out and allow the limb to fall.
- C. Complete the job with a final cut just outside the branch collar.
- Make a sharp clean cut, just beyond a lateral bud or other branch.
Treating Cut Areas
Cut areas don’t need any special treatment. When cuts are made properly at the branch bark ridge, trees are able to compartmentalize, or set boundaries, at the injury (pruning) site. This process helps resist the spread of infection. Wound dressings do not stop decay and actually increase the rate of decay. Therefore, it is best to leave the tree to its own defenses.
Pruning Trees is an Annual Job
If minor pruning is done every year, the job is manageable and the plant remains healthy. A beautiful plant form is retained, and pruning cuts remain virtually unnoticed unless close inspection is made.
However, when plants are neglected over a period of years, major pruning considerably changes the plant’s form. Furthermore, removing large amounts of wood at one time is detrimental to the plant’s health.
Why Topping Hurts Trees
Topping is the indiscriminate cutting back of tree branches to stubs or lateral branches that are not large enough to assume the terminal role. Other names for topping are, heading, tipping, hat-racking, and rounding over.
Topping is perhaps the most harmful tree pruning practice known. Despite more than 25 years of literature and seminars explaining its harmful effects, topping remains a common practice. The process removes 50-100% of the leaf-bearing crown of a tree. Since the leaves are like “food factories,” the tree can temporarily starve.
Cuts made along a limb, between lateral branches, create stubs with wounds that the tree may not be able to close. Decay organisms are given a free path to move down through the branches because trees cannot defend the multiple severe wounds caused by topping.
There are several alternatives to topping. Branches should be removed back to their point of origin. If a branch must be shortened, it should be cut back to a lateral that is large enough to assume the terminal role. A rule of thumb for this is to cut back to a lateral that is at least 1/3 the diameter of the limb being removed. Sometimes the best alternative is to remove the tree and replace it with a species that is more appropriate for the site.
For an illustrated, detailed guide on pruning trees throughout their life cycle, click here.