Most trees should be pruned during the late dormant season (February through March). February through March is generally regarded as the best time to prune most deciduous trees.
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.
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.
Surely there's one chore you can tick off your endless outdoor to-do list—and maybe even get a jump on for spring. 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.
For most trees, the best time for major pruning is late winter to early spring because wounds close faster. Pruning in late summer and early fall may also stimulate new growth, which has little time to harden before cold weather comes.
According to gardening expert Mike McGrath, author of Mike McGrath's Book of Compost, and radio host of the show You Bet Your Garden, the rule of pruning is that you should NOT prune in fall. That's right, nothing and no exceptions.
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.
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.
Plants To Cut Back In Fall:
Lilies. Gaillardia (Blanket Flower) Catmint (Nepeta) Columbine (Aquilegia)
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.
There is never a bad time to remove dead, damaged or diseased branches. But most trees benefit from pruning in mid to late winter. Pruning during dormancy encourages new growth as soon as the weather begins to warm. The lack of leaves after autumn allows you to easily identify branches and limbs requiring removal.
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.
Pruning Too Early
If you prune too early in the season, there's a good chance you'll snip the buds right off their branches, which means no flowers in the spring. Before you cut, do a little research, like with our pruning guide, or just wait to trim until the plant has finished blooming for the year.
Pruning less of the plant but more frequently is by far the best for the overall health of it. We recommend every other month, which comes out to be five times per year. This is the sweet spot for pruning and will help keep everything looking and performing its best.
Also, do not cut back hardy perennials like garden mums (Chrysanthemum spp.), anise hyssop (Agastache foeniculum), red-hot poker (Kniphofia uvaria), and Montauk daisy (Nipponanthemum nipponicum). Leave the foliage. It's important to protect the root crowns over winter.
Don't Prune in Late Summer and Fall
Pruning shrubs in August or early September may encourage a late flush of growth.
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.
Prune back stems to just above a fat bud — called a heading cut — in fall, late winter or spring. These plants have conical-shaped flower heads. I recommend leaving the dry, tan flower heads on the plant to provide some winter interest in your landscape, so I wait to prune these until late winter or spring.
When it comes to evergreen herbs, which include rosemary, thyme, and sage, you only need to prune about once a year, either in early spring or fall. The three fastest growing herbs are mint, basil, and dill.
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.
"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.
Generally, the best time to prune or trim trees and shrubs is during the winter months. From November through March, most trees are dormant which makes it the ideal time for the following reasons: Trees are less susceptible to insects or disease.
The best season to prune trees is while they are dormant, or generally between November and March. This means waiting for them to lose their foliage and cease growth, but before forming buds. For fruit trees such as the apple tree, prune in late winter.