The Best Time To Prune Trees in South Dakota

I think it is fairly common knowledge that when a tree is pruned can make a difference on how the tree responds to the stress of the pruning. And that is correct. There are also a few other reasons why you may want to prune a certain time of the year. This article will cover those topics so you will be able to schedule your tree pruning for optimum success.

Best Time of Year to Prune

The best time of year to prune your trees (across all species) is from winter to very early spring. Around Sioux Falls and the upper mid-west that is going to be any time between December and April. If there is an early spring, April can get into when trees will start breaking buds so before that time is better. We can still get fairly warm temps in November, so waiting until its good and winter is also a good bet.

I usually wait and prune my own trees in March. I try and find that first 40 degree day when it feels like summer. Just make sure you do your pruning before the buds break green in the spring.

Why?

Winter is the best time to prune your trees for several reasons:

  • Everything is dormant. The trees are dormant and not growing and there are no disease or pests that can take advantage of a fresh wound on the tree.
  • The trees can respond quickly to the wound and begin to compartmentalize off the wound right away in the spring.
  • Trees can re-allocate stored energy into other parts of the tree when they begin to grow in the spring.
  • No stored energy is wasted in the pruned limbs since nothing is growing.
Spring time when growth is happening is a time not to prune a tree.

Avoid pruning in the spring once flower buds or leaf buds have broken open. This is the worst time of the year to prune.

Worst Time of Year to Prune

The worst time to be pruning your trees is during the spring when they are growing. This is from when the buds break green until they are either done growing their first push of shoot (twigs) growth or they are at least done reproducing for the season. The easiest way to explain this is this: Avoid pruning between April and July if possible.

Why?

Trees expend a lot of their stored energy from the previous year to put on new growth and reproduce. By pruning when those limbs are growing is to basically waste all that energy. Plus, it will take more energy to begin to compartmentalize the wounds. This is energy the tree had not planned on using. Which can stress the tree further.

Some specific species also have other reasons why they shouldn’t be pruned in the spring. They include birch, elm, and some oaks. This is due the increased chance of attracting pests or disease. In Sioux Falls, all ash must not be pruned or removed between Memorial Day and Labor Day. That practice should be continued for anyones ash trees now that emerald ash borer is in the area. It will help reduce the beetles spread. You can learn more about that HERE.

What about Summer?

Summer is the second best time to prune your trees. After they have finished with the spring growth and the fruit (seeds) are matured, you can prune with little excess stress to the tree. A lot of people like to prune in the summer so they can see where they need to prune for clearance. And that is acceptable. But the benefits of waiting until winter are so much better for the tree in my opinion.

What about Fall?

Fall is that second worst time to be pruning. It can actually have more long term risks to a tree than the immediate stress of spring pruning. This is due to the wood decay fungi that are actively reproducing during the fall. Falls are traditionally another wet period. Damaging wood decay fungi make their mushrooms in the fall and spread out their spores in the wind and wet weather. If fresh wounds are made to the tree during that time, decay fungal spores can land on the wound and enter the tree before the tree has time to internally compartmentalize off that wound. This can increase the chance of early internal decay within trees that can cause a lot of problems later in life.

 

A lot of difference can be made just from when you prune. How the pruning is done is still far more important than when, but timing is an important factor to pruning and tree health. To learn more about proper pruning or to find a certified arborist to prune your trees, you can start your search with the International Society of Arboriculture.