Any gardening expert will tell you, (contrary to what you may believe) that pruning encourages new growth just when the plant is trying to go dormant and new growth doesn't have enough time to harden before the first frost and freezing temperatures hit. Pruning at this time of year will severely weaken the plants.
"As soon as trees and shrubs go into dormancy, pruning can begin," he said. "And you can prune up to the time when buds begin to plump up." From mid-November to mid-March, you can shape and thin your deciduous plants in preparation for the spring season ahead.
The rule on fall pruning is, generally speaking, don't prune in fall. But there are a few trimming tasks you can take on with confidence, provided you approach the job with self-control and a plan. The timing window for these pruning chores is from Thanksgiving to the New Year.
It's a common misconception that tree maintenance cannot be done during the winter months, or that tree care companies don't operate during this time of the year. The reality is that winter is a good time for pruning and tree removal services.
Spring flowering shrubs and trees.
Shrubs and trees like lilacs, azaleas, and others will grow best when they are pruned right after they flower in the spring. Avoid pruning them in the winter as it may stunt their growth.
You will want to prune your trees when the temperatures are going to be fairly constant for at least a couple of weeks. If you trim your trees when the temperature is 60 degrees, and overnight, the temperature drops below freezing, your trees could be damaged.
By not cutting back the statuesque achilleas, eryngiums, perennial astilbes, sedums, alliums and many ornamental grasses, you can enjoy their structure against a winter sky. The sight of their stems silvered with frost adds a whole new level of interest to the garden.
In fact, it is better to prune a little at a time than to make drastic cuts. For plants that shed their leaves (deciduous plants), the best time for winter pruning is from the beginning of November to the end of February. To prune evergreens you can start later, from mid-December, and continue until February.
According to Ramsey County Master Gardener Volunteers, February is the best time to prune your trees. In February, harmful tree diseases are at a minimum and deciduous trees have already “hardened off”, meaning they have prepared for winter dormancy.
Did you know that if you prune too late in the season, you stimulate new growth, which will not have time to harden off before the first frost, which will be coming soon to our neck of the woods. This can weaken and damage the plant, so its best to leave the pruning until spring.
No matter what type of shrub you have, fall pruning can stimulate late-season growth that may not have enough time to harden. This can weaken and damage the plant—especially if there's an early frost. Instead, wait until winter and trim bushes when the plant is in deep dormancy.
The Best Time to Prune Evergreens
To maximize flower buds for the following year, prune flowering evergreens right after they bloom. One surefire tip: don't prune evergreens in late summer or fall. Pruning late in the growing season leaves plants susceptible to winter damage.
Winter Pruning is Less Stressful for Your Trees
Pruning during the active growing season can cause stress for your trees and can stimulate additional growth that won't be able to harden before the temperature drops. Trees go dormant during the winter months, making it the perfect time to prune.
Don't shear the branches of spring flowering shrubs (Forsythia, Lilac, New Mexico Privet, Spirea, Flowering Quince, and others). These shrubs produce flowers on last year's wood, so removing old growth will reduce or prevent flowering. These plants should be pruned immediately after they are done blooming.
When is Late Winter? Late winter is 4 to 6 weeks before spring thaw begins. This could be any time in January to May, depending on your climate. Use your average last frost date and count back.
An improper cut like a flush cut (cutting too close to the trunk) or a stub cut (cutting too far from the trunk) can cause irreversible damage to a tree. A flush cut removes the branch collar and leaves a large wound in the side of the tree that won't heal properly.
Pruning during the growing season always stimulates new growth. During summer's heat, having to produce that ill-timed new flush of growth greatly stresses a tree. Pruning in the fall is even worse as it prevents the tree from going into a natural dormancy. The exception is heavily damaged, disease or dead wood.
As a general rule, prune spring-blooming trees immediately after they flower. Prune trees that bloom in the summer or fall in late winter or early spring before the end of their dormancy. Routine pruning of dead or dying branches can be done at any time.
Cutting plants back before the first frost and before plants are in full hibernation could cause them to activate dormant buds. If they push out tender new growth before the onset of winter, these new shoots will be killed by the inevitable still-to-come freezes.
Avoid pruning in fall.
Pruning cuts can stimulate new growth that, unfortunately, will be killed as temperatures drop to freezing. Trees and shrubs reduce their energy production as the growing season ends, so new growth in autumn will use a plant's stored energy reserves.
Fall is the time to clean up any dead, damaged, dangerous, or diseased branches but otherwise, hold off. Most pruning tasks are best done in the winter or early spring when plants are still dormant and not budding or blooming. That's the time to prune for better appearance, structure, air flow, and so on.
It's important to cut back foliage in the fall to protect flowering plants from disease and give them a clean start for regrowth as winter starts to turn into spring. However, there are some plants you can keep around through the winter since they benefit wildlife and still offer visual interest for your home.