News release: Pruning Trees, Part I

Tim Baker, MU Extension Horticulture Specialist
102 N. Main, Suite 1, Gallatin, MO 64640

Release Date: February 6, 2014

Headline: Pruning Trees, Part I

One of the common questions I get as a Horticultural Specialist is “When is the best time to prune my trees?”  Since we are getting closer to the ideal time of the year to prune deciduous trees, I thought I would devote my next two columns to that topic.

Late winter and early spring is the best time to prune most trees. This is especially true for fruit trees, but this is also a good time of the year to prune your other deciduous trees and shrubs as well.  It’s also getting close to the time of the year to apply dormant sprays.  Generally, it’s a good idea to prune first, and then apply your dormant spray, since you will have less wood to cover with your dormant oil.

Before I start, let me backtrack just a bit and say that there are a few exceptions to pruning deciduous trees and shrubs right now.  If you are dealing with spring-flowering shrubs, for example, it’s best to wait until after they have bloomed before you prune.  If you prune now, you’ll be removing all the flower buds, and your shrub will not give you a spectacular show if you remove all its blooms.  Forsythia is a good example of a spring-flowering shrub.

But for fruit trees and other trees and shrubs that are not kept for their showy spring blossoms, late winter is a good time to prune.  By that time, we are hopefully past the worst that winter has to offer.  The plant is getting ready to come out of dormancy.  So if you get your tree in good shape, the pruning cuts will quickly heal over, and the plant will be off to another season’s growth... with a bit of trimming to keep it in line and give it the best form.

Good form is an excellent reason to prune, but it is best started early when the tree is young.  Fruit tree growers have developed pruning for form to a fine art.  But it’s critical for the long-term health of the tree.

When you prune for form, you want to allow branches to grow that have a wide angle relative to the trunk.  Narrow branch angles are weak, and are likely to break in high wind or under a load of ice, so these should be removed. When fruit tree growers select branches with wide angles, they are trying to increase the useful life span of their tree.

If you are dealing with an older tree which has been neglected, or not pruned correctly during the first few years, there will be a limit as to how much corrective pruning you can accomplish.  Large branches with narrow angles will probably have to be left in place.  If you do try to do some corrective pruning on an older tree, don’t try to do it all on one year.  It’s best to spread out your corrective measures over several years.

Some things are easily addressed in that first year of pruning.  If there are root suckers coming out from the base of the tree, those can all be removed.  Similarly, water sprouts that come up from branches can be removed.

Those are some of the general guidelines that we think about when pruning trees or shrubs. There are excellent books and other guides available, if you want to learn more. Doing a good job of pruning is especially critical for fruit trees. I’ll discuss them in greater detail in my next column.