Tree topping, sometimes called “hat-racking” or “heading,” is a widely practiced but severely damaging method of tree pruning. This process involves the indiscriminate removal of a tree’s upper crown, often leaving behind large branch stubs. Professional arborists condemn this technique because of the physiological and structural harm it inflicts. Topping is not a form of proper tree care and often results in a short-term fix that leads to long-term decline and increased danger.
The Mechanics of Topping
Topping is defined by the drastic, non-selective cutting of large, upright branches and main leaders to a predetermined, arbitrary height. This action typically removes between 50% and 100% of the leaf-bearing crown, leaving behind only short, vertical stubs on the main limbs. The goal is often a rapid reduction in the tree’s height or spread, perhaps due to a perceived safety concern or interference with utility lines or buildings.
Many property owners choose topping because they believe it will prevent storm damage or control the tree’s size permanently. The practice fundamentally misunderstands the tree’s biology and growth response. Unlike proper pruning, which makes cuts back to a lateral branch or bud, topping ignores the tree’s natural growth habits and defense mechanisms. The resulting bare, mutilated structure is a clear visual indicator of the damage inflicted.
Biological Damage and Stress
The sudden removal of such a large portion of the canopy triggers a survival mechanism. Since leaves are the tree’s food factories, the drastic reduction in foliage significantly impairs its ability to photosynthesize. This process, the conversion of sunlight into energy, is interrupted, causing the tree to starve and deplete its stored energy reserves at an unsustainable rate.
The wounds left by topping are large, open, and incapable of being sealed by the tree’s natural defense process, known as compartmentalization. Unlike smaller cuts made just outside a branch collar, the large stubs created by topping cannot close over, leaving the inner wood exposed. These gaping wounds become entry points for wood decay organisms, fungal pathogens, and insect infestations.
Sunscald and sunburn occur on the previously shaded bark of the trunk and interior branches. The dense canopy normally protects the delicate living tissues beneath the bark from direct, intense sunlight. The sudden exposure to high heat and light can cause tissue death, leading to bark splitting and cankers, further weakening the tree’s defense against disease.
Why Topped Trees Become Hazardous
Ironically, topping often increases the very hazard it was intended to prevent. In response to the loss of its crown, the tree rapidly pushes out numerous, thin shoots known as epicormic growth or “watersprouts” from dormant buds directly below the cut stubs. This dense, brushy regrowth is a desperate attempt to restore photosynthetic capacity.
These new sprouts are structurally unsound; they are only superficially attached to the outermost layer of the parent branch. They develop without the strong, overlapping wood tissue, or branch collar, that anchors a naturally grown branch. This weak attachment point means that as the watersprouts grow quickly and become heavy, they are prone to breakage.
Within just three to five years, the topped tree develops a dense, broom-like crown of weakly attached limbs, which offers far greater resistance to wind than a naturally shaped canopy. During a storm or high wind event, these limbs are much more likely to snap off at the point of the topping cut, turning the tree into a significant liability. The combination of weak regrowth and internal decay spreading from the original topping wounds makes the tree more dangerous than it was before the procedure.
Recommended Alternatives to Topping
Arboriculture offers several alternatives for managing tree size and reducing risk without resorting to topping. For safely reducing the height and spread of a mature tree, the preferred method is a crown reduction. This technique involves selectively cutting a branch back to a lateral branch that is large enough—ideally at least one-third the diameter of the removed portion—to assume the terminal role.
Crown reduction maintains the tree’s natural shape and minimizes stress by ensuring the tree can seal the smaller, correctly placed wounds. Another effective technique is crown thinning, which involves the selective removal of interior branches to improve light penetration and air circulation. Thinning reduces wind resistance across the entire canopy, which lowers the risk of storm damage while promoting overall tree health.
If a tree is too large for its location and cannot be safely or healthily managed with proper pruning, the action is often removal and replacement with a species appropriate for the site. Consulting a certified arborist ensures that only approved pruning techniques are used, safeguarding the tree’s longevity and structural integrity.