So far this seems to be the winter that wasn’t! But the forecast calls for colder temperatures ahead and historically we have had some heavy snowfalls in March and even April, so all is not yet lost. While we can’t be sure the ground is frozen I think it is safe to say that our woody plants are in dormancy and that makes February and March the best time of the year to prune them.
An important part of maintaining trees and woody landscape plants is something that most of us do not even think about. The Minneapolis Parks forest department prunes boulevard and park trees regularly to remove dead or dying branches or branches that are rubbing against each other. We should do the same with our own trees and woody shrubs.
Pruning is important to the health of trees and shrubs – so remove branches that are dead or dying as a result of disease, severe insect infestation, damage from animals or storms, or branches that are rubbing against each other. Crossing branches tend to rub against each other and develop wounds. These wounds allow for disease and pests to get under bark and into stems, causing problems for the plant down the road. Pruning opens up tree canopies, increasing airflow and light to stems and branches. Pruning will encourage flower and fruit production.
Pruning also allows us to improve the appearance of our woody plants. You may want to control the size of your plant and/or maintain its nice natural shape. When a tree or shrub is pruned properly you should not be able to tell that it has been pruned.
“Topping” is not the appropriate way to prune a tree or shrub. Topping is the severe pruning of a tree by cutting back all the top and outer branches of the tree. A topped tree usually has a flat or bald look about it. Very thick branches are lopped off in the middle and the resulting look is very unnatural. Besides looking very unattractive the tree is severely damaged and very often does not survive this type of pruning. Topping trees results in a dramatic reduction of leaves in proportion to its size. There are fewer leaves to produce food for the tree through photosynthesis, which results in the decline of the tree’s health, and its ability to resist disease and insects that may be attracted to the tree.
It may also be necessary to prune a tree to protect people or property. This can be necessary when dead or broken branches are in danger of falling, or there is a narrow-angled crotch between two branches. Narrow crotches are weaker than wide angled crotches. Branches that come out at wide angles from the trunk are able to withstand adverse weather and other environmental stresses.
You may wish to prune trees or shrubs that obscure the entry to your home or be required to trim ones that obstruct the vision of drivers or pedestrians. Trees that are interfering with street or traffic lights or utility wires should be pruned. (The utility companies will trim the trees that interfere with their wires but they seldom do it in the proper or an aesthetically pleasing way.)
The best practice of pruning is thinning. That is the selective removal of branches — completely removing them back to the stem or another branch. Thinning maintains the natural shape of your plant and as stated earlier, if your plant is pruned properly you should not be able to tell that it has been pruned. The advantages of thinning over topping are that you are not drastically reducing the number of leaves at one time — the cutting wounds are closer to the stem and will heal faster, and new growth is stimulated over the entire tree and not just at the ends of branches. Proper pruning should begin in the first or second year after planting and continue over the life of the tree.
You may be able to prune shrubs and smaller trees yourself, but for larger trees it is best to hire a certified arborist. Trees are an important investment in your landscape and you should protect this investment by hiring a knowledgeable and trained professional to care for your trees, just as you would hire a professional electrician, plumber or carpenter to maintain your home. No reputable tree trimmer should suggest, “topping” your tree. For info on hiring a certified arborist visit extension.umn.edu/garden/yard-garden/trees-shrubs/how-to-hire-a-professional-arborist/.
I like trees because they seem more resigned to the way they have to live than other things do. – Willa Cather