2 minute read
Cold and Snow? Grab Your Pruners
ELLA KYLLO • GARDENER, ISA CERTIFIED ARBORIST
Late winter is the perfect time to cozy up indoors with thick woolen sweaters, mugs of hot tea and other comforts to carry us through the darkest season. Outside, trees have dropped their leaves, drawn their energy resources inward and are blanketed by a thick, insulating layer of snow.
As tempting as it is to stay inside until warmer days, winter is also one of the best times of year to get outside and prune trees. From winter to early spring, the horticulture staff at the Arboretum is out in force, skillfully pruning trees across the grounds.
A targeted effort is made during this time to prune oak, crabapple, apple, mountain ash and hawthorn trees, when disease transmission is at a minimum, and horticulturists can clearly see the form and structure of the bare branches.
While trees are dormant, so are the pathogens, and transmission of devastating oak wilt fungus and fire blight bacteria are at their lowest in the winter months.
The period from November to March is considered the safe period to prune oaks, while February to April is the safe period to prune trees that are affected by fire blight. This includes crabapples, apples, mountain ash and hawthorn trees.
The Arboretum is home to numerous oaks that are estimated to be as old as 200-250 years old, and winter pruning helps to ensure their health and longevity.
During the winter, the branch structure of trees is clearly revealed, and horticulturists can prune any branches that need attention. This includes removing dead, broken or rubbing branches, and raising lower limbs that are causing obstructions.
Taking a drive along Three-Mile Drive after a fresh snowfall is an excellent way to observe the natural branch structures and appreciate the architectural forms of trees.
For an experience of solitude that only fresh snow and the grandeur of mature trees can provide, embark on a snowy hike along Three-Mile Walk or the Arboretum’s snowshoe and ski trails this winter.
Learn more about proper pruning techniques for trees and shrubs from the University of Minnesota Extension. Visit their website at extension.umn.edu and search “pruning,” or sign up for a pruning course at the Arboretum at arb.umn.edu/gardening-classes.
