Differences Between Tree Topping vs. Crown Reduction

Katy Willis
Written by Katy Willis
Reviewed by Tara Dudley
Updated May 9, 2022
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Highlights

  • Crown reduction is the best option for tree pruning

  • Only trees with severe damage should receive tree topping

  • Deadwooding removes dead, dying, or diseased branches

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Crown reduction and tree topping are often confused, and many people think they're the same practice. But there are significant differences. Crown reduction is a carefully selective pruning process that aims to control the size of the tree and improve health, shape, and appearance with precise cuts. 

Topping is a banned practice in many areas and is generally frowned upon by professional arborists because it involves indiscriminately removing all the top growth of a tree and can easily weaken or kill it. 

That said, there are times when topping is the only way to save a tree. And then there's deadwooding, which involves only removing dead or dying portions of a tree.

What Is Crown Reduction?

Crown reduction is the key method professional arborists use to control the shape and size of a tree. It reduces the size of the crown while leaving the structure of the crown unharmed. An arborist selectively removes live branches to decrease the height and spread of the crown and to open up the crown to increase airflow through the canopy. 

This process uses drop crotch pruning cuts. Essentially, the arborist selects parent branches that have a lateral or side branch of at least one-third of the diameter of the parent branch. 

The diameter of the side branch is vital because, if it's less than a third of the size of the parent branch, it won't be able to carry enough water and nutrients and take on the terminal growth responsibility of the parent branch. 

Once the arborist identifies a suitable parent and side branch, they’ll cut the parent branch just above the crotch, or the point from which the lateral branch grows. 

What Is Tree Topping?

Closeup of a topped tree
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Tree topping should rarely be used and, in many areas, it's a banned practice for city-owned trees. Basically, the tree receives indiscriminate heading cuts that ruin the crown structure in a misguided attempt to control tree size.

This practice is sometimes called hat racking because, once the arborist removes the tree's canopy and reduces the majority of upper branches to stubs, the remnants of the tree resemble a hat rack. 

The arborist removes the parent branches without consideration of the size of the lateral branches, and where lateral branches are too small, they cannot take on the terminal responsibility of the parent branch. 

Tree topping creates all kinds of problems and can easily kill a tree or make it susceptible to diseases and insect infestation. It also ruins the tree's natural growth habit because the side branch can't cope with the responsibilities of the cut parent branch, so lots of weak, leafy growth sprouts from the cut on the parent branch. This growth creates a dense canopy that's prone to fungal pathogens because there's not enough airflow.

What Is Dead Wooding?

Deadwooding is another tree maintenance service often confused with tree topping or crown reduction. Deadwooding involves seeking out and removing diseased, dying, or dead limbs. Consult with a local arborist to see if your tree needs deadwooding. 

This practice helps to limit the spread of disease, makes the tree safer, and reduces the risk of falling or broken limbs.

When Should You Use Crown Reduction?

Gardener wearing a vest trimming a tree branch
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Crown reduction should be the primary method you opt for to control the height and shape of your trees. It's important not to over-prune, but with large, mature trees, periodic crown reduction helps to keep them safe, healthy, and manageable. 

To avoid shocking your tree, never remove more than 25% of its canopy at any one time. 

Never opt for topping when crown reduction is an option. Hire an arborist to prune your trees. While most arborists generally consider winter the optimum time; they can perform crown reduction any time apart from spring when the tree is just starting to produce leaves.

When Should You Use Tree Topping?

While the ideal answer is "never," there is one time when tree topping may be the only option to save a tree. If a tree has suffered severe damage from a storm or a natural disaster and much of the canopy and crown is significantly damaged, then tree topping might be the only choice.

In such cases, when enough large limbs are split, seriously injured, or at a high risk of falling, then an arborist may recommend topping. You can, of course, remove the tree and plant a new one in its place. However, if you'd rather hang on to the tree you've got, then tree topping makes the tree safe and gives it a chance to recover. Note, however, that it may not work and, if the tree is already too stressed, the stress of topping may kill it.

When Should You Use Deadwooding?

If your tree shows signs of disease, you've got a split branch, or a dead limb, then you need a deadwooding service. The tree surgeon will get up near the tree's crown and identify which limbs need removing. 

Remember, from the ground, you may not be able to see the full extent of the problem. So, when your chosen pro gets up there, they may find that multiple branches are affected or that, while you thought you had a single limb with storm damage, you've actually got a significant infestation of borers or a disease that's spreading from limb to limb.

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