Correctly Pruning a Tree
Healthy trees usually resist wind, snow and ice without breaking. However, sometimes trees need their branches cut to develop good crown structure, remove dead, cracked, diseased or insect-infested wood, or prevent contact with a building or powerline. Cutting a tree’s branches is called pruning. No branch should ever be removed unless necessary, but if your tree needs to be pruned, make sure it is done correctly the first time to avoid permanent damage.
Why “topping” isn’t right
Topping is a common and harmful trimming technique that cuts off all parts of a tree above a certain height or limb size. This technique creates many large wounds that close slowly, leaving the tree open to decay, disease and insect attack. It is difficult and sometimes impossible to reverse the effects of topping. This one action can destroy a tree’s structure, health, beauty, value and even take its life.
After topping, the cut branches will resprout and grow new branches and leaves, and the tree may look good (Figure 1), but it is not in good shape. The new branches will be overcrowded and catch wind like open umbrellas, increasing the strain on the larger limbs. As these new branches grow, they expand into one another, creating pockets of decay in the space where bark is trapped. Fast growing limbs also are weaker than normal, increasing the chance that they may break off from their own weight.
Dense and rapidly growing limbs of topped trees must be removed to reduce the chance of property damage or injury. Removal of these crowded branches is part of an expensive cycle of trimming that can be avoided by properly pruning the tree from the start.
Proper pruning techniques maintain the natural form of the tree (Figure 2). Proper pruning also reduces the size of the wounds and length of time the tree is open to insects and decay. While it may cost more up front, a properly pruned tree will be healthier, stronger, safer and less expensive to maintain in the long run.
When pruning is needed, get at least three estimates. Insist on a signed contract before work begins. The contract should show cost, dates of work, exactly what will be done and when payment is due. Terms like trim, prune, reduce height or remove are too vague and should be more detailed.
How to hire an arborist
Questions to ask an arborist
- Why does the tree need to be pruned?
- Which and how many branches will be removed?
- Will you park a truck on my lawn?
- Do you use spikes for climbing? (Spikes should never be used on living trees except for removals.)
- Will you cut the main trunk? (If yes, the tree may be in the wrong place, discuss other options.)
- If the tree is being removed, will you grind the stump? Or, how tall of a stump will be left?
- What happens if the pruning damages another tree? A house? A car? A person? (Also, check with your insurance company to make sure you are covered.)
- Are licenses and insurance current? (Expired credentials are a red flag.)
Know the terms
- Cleaning – removes dead, dying, diseased and damaged branches
- Directing – removes branches to redirect growth away from buildings or improve tree form
- Raising – removes lower branches for traffic or to improve visibility
- Reduction – reducing a tree’s height or spread using research-based rules
- Thinning – selective branch removal to improve structure or reduce weight on branches
- Topping – cutting all branches off at a specific size or length
Again, no branch should ever be removed unless necessary, but if your tree needs to be pruned, be sure you do it right the first time. Download a free United States Forest Service Tree Owner’s Manual.
Last Reviewed: October 2020