Why Is “Topping” a Tree a Bad Idea?

Unfortunately, many trees are planted in locations in which they outgrow the space available to them. When such trees are situated under powerlines, roof lines or other overhanging structures, they must often have their height reduced to avoid problems.

However, cutting the tree’s primary leader (its main stem) at an arbitrary height can quickly cause the tree to enter a downward spiral, which will ultimately lead to its demise. But this practice – called “topping” – is unfortunately common, despite the threats, it presents to trees.

Why Does Topping Harm Trees?

Topping a tree is harmful because it typically involves making pruning cuts at improper places along the trunk. A tree’s trunk should usually not be pruned at all; but, if it is imperative that you do so, you must make the cuts just beyond a place called a node. Trees are equipped to repair the damage that occurs in these places, but when cut far from these regions, trees almost always become colonized by fungi and bacteria. Topping usually requires that you make these types of destructive, internodal cuts.

Additionally, trees who sustain damage to their central leader (trunk) are no longer able to grow in the way they should. Trees grow in height at locations called meristems, which are located at the distal end of the trunk. With this meristem removed, the tree will spend a lot of resources trying to cope with the damage, which will lead to stress and place it at further risk of decay.

Additionally, when a tree is topped, it often responds by producing a litany of quickly growing, poorly attached branches called waterspouts. These new branches typically look terrible and represent a safety hazard, as they are more likely to fail than properly formed branches are.

What Are the Alternatives to Topping?

Unfortunately, there isn’t much that can be done to tame a tree’s height. Skilled arborists can occasionally carry out a procedure known as a crown reduction, in which the entire size of the canopy is reduced. When doing so, arborists avoid making internodal cuts and try to avoid harming the central leader at all. It is rarely possible to remove a significant amount of height by doing so, but you may be able to reduce a tree’s height slightly by having such a procedure performed.

The better option is to simply have the tree removed. Although this is often heartbreaking to property owners, there is little else that can be done in many cases. After the tree is removed, it can be replaced with a tree that is of the appropriate size for the space available.

This is one of the reasons that tree selection is so important when planning new installations. If for example, you are trying to plant trees beneath a power line, you’ll certainly want to select a western redbud, Japanese maple or crepe myrtle, rather than a jacaranda or eucalyptus tree, which will quickly reach the height of the overhanging power lines.


If you are faced with a tree that is rapidly outgrowing the space available, give your friends at Evergreen Arborist Consultants a call. One of our trained arborists will visit your property and assess the tree in question. We’ll then provide you with recommendations to address the situation and carry out the work if so desired.