In our last article, we described the 5 reasons that you should never top your tree. Not only can the practice be damaging to the tree, and expensive in the long run. But what are we to do if it is necessary to reduce the size of a tree? Most arborists agree that Crown Reduction is preferred to topping. Compared to topping, reduction helps maintain the form and structural integrity of trees.
To recap, Crown Reduction is the selective, strategic removal of branches, all the way back to healthy growing lateral branches. This practice aims to develop a new central stem leader at the top of the tree. To help empower you in this process, we’ve cut through the clutter to find the top five basics of Crown Reduction.
The 5 Basics of Crown Reduction
- Use the “Drop Crotch Pruning Technique” – selectively pick branches, and cut back to a lateral branch or trunk, which looks like a junction of two legs, or the crotch. Never leave large stubs behind.
- Never cut off more than 20% of the tree. If it’s necessary to prune more than 20%, either because of damage or dangerous conditions, trim the tree in increments. 20% now, then a healing period, and you can finish the job at a later date- Usually about a year later, if you can.
- Develop a new central leader at the top of the tree. The new central leader should be the tallest, straightest, healthiest stem in line with the rest of the trunk.
- When reducing a leader branch, cut back to a lateral branch that is large enough to assume dominance. A lateral branch that is 30% of the size of the original parent branch will be your ideal candidate. Any larger than the 30%, and you run the risk of producing multiple, weaker shoots, that do not follow the intended pruning direction- Any smaller, and the branch may not be strong enough.
- As a general rule, when reducing the size of the tree, one should try to thin out the longer branches while keeping the crown of the tree balanced.
Mature trees are a valuable resource that are not easily replaced. Careful, well thought-out pruning may cost a little more in the short run, but is well worth the effort in long term health, aesthetics, safety and future costs associated with the tree. If you are hiring a tree professional to do the job for you, be sure they are familiar with the above techniques. If you are trimming the tree yourself, be careful, and educate yourself on the most important pruning basics.