Ask an Arborist: What are the Rules of Pruning?

This is part two of a  three-part dormant  season pruning series. Watch part three,  the ABC’s of Pruning to learn how to prune your tree and catch up on part one, why do I need to prune?.

Tree pruning, trimming, or cutting is an ongoing process throughout the life of your tree. After selecting the right tree and carefully planting it, early pruning is the most important thing you can do for a young tree.

But one of the most common mistakes made in pruning trees is removing too many branches, which can impact the growth rate of the tree. So here are five rules (or “factors”) — a phrase first coined by Mark Peterson of the San Antonio Water System — you can follow to make sure the pruning “dose” is directed in the most effective manner, without impacting the rate of growth.

Five Factors for Form and Function:

1. Branches and leaves will occupy at least ⅔ of total height.
2. All branches will be <½ the diameter of the trunk, at point of attachment, this keeps branches from competing with the trunk.
3. No more than ⅓ of live foliage will be removed in a year. This is a heavy pruning dose for a young tree; ‘less is more’ in most cases.
4. All final cuts will be less than 1 inch in diameter, this means cuts close over quickly, limiting chances for decay organisms.
5. Limit of 5 pruning cuts per year.

Proper pruning will save you money and give you a safer more beautiful, healthier, and easier-to-maintain tree. Remember what you do to your tree in its first few years of life will affect its shape, strength, and even its life span. If we focus our pruning efforts strategically – with the right tools – we can develop long-lived urban trees! For  more pruning resources visit treesaregood.org or University of Florida IFAS Extension.

Watch part one of the dormant pruning series here.