In general, the best time to prune trees in Minnesota is sometime between the late fall and the flowers blooming in spring. But there are several things to consider when deciding what time of year to prune your tree. Here are some general guidelines to consider when planning to prune:
Know Your Tree
Pruning requirements of trees and shrubs will not only vary according to species, but it will also depend on the purpose of pruning. Knowing the species of your tree and the associated diseases and/or pests that are attracted to that tree are important. In Minnesota, oak trees are affected by Oak Wilt--a fungal disease that kills thousands of oak trees every year. This disease spreads through root grafts radiating outward from a central infected tree. It also spreads via beetles, who are attracted to freshly cut oak trees, that carry the fungal spores from tree to tree. The timing of oak pruning should be carefully considered as you want to avoid a time when beetles are active. Because of this, oak trees should be pruned in the winter months when the trees are dormant and to prevent the spread of oak wilt.
For shrubs and fruit trees, pruning should take place immediately after flowering. If you wait until the new buds have formed, you will likely prune off the buds for next year's flowers. Just another reason to know your species before you start pruning.
If you need help identifying a tree species, contact an Arborist for a free consultation.
Pruning for Safety
One caveat for pruning is when safety is the primary reason to prune. Old, dead, and diseased branches can become a hazard and pruning of these branches should occur as soon as possible. If an oak tree needs to be pruned for safety reasons during a high-risk period for oak wilt, there are measures that can be taken to cover the wound and reduce the risk of attracting beetles.
As mentioned, pruning during the winter months is a very common practice as it results in a burst of new growth in the spring. If you prune too late after new growth has started, you can limit the plant’s bloom potential for the year. When pruning in the winter it is best to wait until the coldest part of winter has passed for some species of trees. Maple, walnuts, and birch trees may bleed when the sap begins to flow. Winter pruning is also great for arborists as the harder ground provides them easier access to trees and the bare canopy makes branches easier to see and handle. Additionally, homeowners yards receive much less damage from falling branches when the ground is frozen.
Summer is a good time to prune trees if you are looking to complete structural work or control growth. Suckers, water-sprouts, and crossing branches can be easily removed during the summer and energy will be directed toward remaining branches. Also, a shrub that is outgrowing its allotted space can be trimmed to impact the direction new growth will take. Any pruning that intends to slow the growth of branches you don’t want, or to slow development, should be completed after seasonal growth is complete. Keep in mind that the main purpose for summer pruning should be for corrective purposes (e.g. defective limbs that hang down under the weight of leaves or you are trying to reduce total leaf surface).
Avoid Pruning in the Fall
We know that when fall clean-up is in full force, your pruning tools are right there next to your rakes and leaf blower. Do what you can to avoid pruning your trees and bushes during the fall and keep the pruning tools in storage. Fall pruning could cause more harm than good as it is a time of year when trees and plants are preparing to go dormant. Since trees and plants are preparing for winter, any pruning that takes place will severely weaken them.
Avoid Stressful Situations
Just like humans, trees can become stressed. And stress levels increase during trying times like:
- Hot dry periods
- Extreme winter cold
- Injured trees (e.g. storms)
- Newly planted trees
- Root disturbance
These are all situations that cause stress for trees and plants. Pruning a tree that is stressed can make matters worse so be mindful of these situations and consider managing the stress, before pruning (e.g. water your tree during droughts or let it heal if injured).
Knowing when to prune plants and trees will keep them healthy in the long-term while setting them up for a season of robust growth. Be sure to take into consideration the overall health of the plant prior to pruning. Proper pruning will promote tree health and save money by helping with disease management.
You should take advantage of the prime pruning period and contact Precision Landscape & Tree about a free dormant pruning consultation. Our certified arborists know how to keep trees healthy. Newly planted trees may need to be pruned every year to obtain proper form and strength. Old mature trees may only need to be pruned every five years. Whatever the case, we will properly trim your trees while keeping tree health a top priority.
Related Article: 5 Must-Have Pruning Tools