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.
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.
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.
The best time to prune is after flowering. If the plant needs to be renovated, or severely reduced, this can be done late winter and early spring just before growth begins.
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.
To avoid certain diseases, pruning in the late winter is especially great. Avoid Oak Wilt disease by pruning oaks between November and March.
Never prune too early in the winter, as incisions can dry out if the temperature drops well below freezing. When pruning, first prune out dead and diseased branches, especially those caused by the winter's snow and ice. Unwanted lower branches on all evergreen shrubs and trees should also be removed in late winter.
If you want to prune in fall, wait until trees drop their leaves and are dormant—usually October or November. After leaf drop, you can see the tree's structure and identify disease and insect problems more easily.
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.
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.
During excessively cold temperatures
It's minor, but it could impact the look of a plant or create a haven for insects and diseases later. Don't prune when the temperature falls below 25°F.
Trees that bleed.
Trees like maples, birches, or elms can produce a heck of a lot of sap if you make the decision to prune them during the winter months. Instead, your best bet is to wait until summer and avoid a mess.
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.
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.
Choose the Right Time
Likewise, prune in the early morning or late afternoon to avoid the newly cut ends of branches becoming scorched by the hot sun. Wait 48 hours after rain to prune, to allow plants to dry out and avoid fungal diseases. When pruning, make cuts just above leaf nodes, or buds.
As a general rule, a light summer pruning can be performed on most deciduous trees and shrubs. Heavier pruning should be performed when the tree is dormant, preferably in late winter before active growth begins.
The period between the full and new moon (third and fourth quarters) is best for harvesting, slowing growth, etc.
Late winter is a good time to prune most plants. Because plants and their pests are dormant this time of year, pruning cuts can be made without the risk of pests and pathogens entering the tree through the wound.
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.
Municipalities and homeowners often remove the lower limbs for pedestrian and vehicular clearance or to let the sun shine in for grass to grow. Mature trees, especially evergreens, benefit when healthy lower branches are left intact. Removing large limbs can increase the risk of decay.