1. Always Remove Broken Branches
Winter is hard on our smaller woody shrubs, fruit trees, and ornamental trees. Ice and wet, heavy snow easily break branches or bend them to the point where they break or split.
Regardless of the recommended pruning time for a plant, it’s always okay to remove a broken, dead, or clearly diseased branch at any time of year. A proper cut will remove the strain on the rest of the plant, minimize further damage, and leave a clean wound to heal.
2. Double-Check If Branches Are Dead
Some branches look dead, but in winter, it is often hard to tell. If the bark has fallen off or the twigs snap cleanly under light pressure, the branch is probably dead. To check, lightly scratch the bark with your fingernail and look for color. If it's green, right under the bark, it usually means the branch is still alive.
However, if you are having doubts, it’s okay to wait until the buds start to fatten up in late winter or early spring. You’ll then be able to see what portion of the branch is still alive, so you don't accidentally prune it.
3. Skip Ornamentals Blooming on Old Wood
Not every woody shrub or tree should be pruned in winter. While pruning during the dormant season is the norm for many fruit trees and ornamental shrubs, it isn’t a universal rule. Many spring-flowering shrubs, including lilacs, bigleaf hydrangeas, rhododendrons, and lilacs, bloom on what is referred to as old wood—flower buds that were formed during the previous summer or fall. Pruning them in winter means you’ll cut off many, if not all, of the flower buds, reducing or eliminating flowers in the coming spring.
As a general rule, plants that bloom early in spring on last year’s growth are pruned right after they finish flowering. Those with summer or early autumn bloom periods bloom on what is called new wood and are usually okay to prune in winter. However, this isn’t a hard and fast rule. Apple trees bloom in early spring, but are pruned in winter. To be sure, identify the shrub or tree and search online using the species or cultivar name to find out whether it is blooming on old or new wood.
4. Go Easy on Evergreens
In areas with severe winters, cold winds and sunshine pull moisture out of the needles of evergreens. The tree or shrub cannot replace it because the ground is frozen (and so is the water in it). As a result, the desiccated needles on the tips may start to look brown and dead, but the twig itself may be fine. Deciduous trees and shrubs don't have that problem because they drop their leaves before winter.
When pruning evergreens in winter, only remove broken or hazardous branches, and wait until spring to assess twig dieback and do any aesthetic pruning then.
5. Look Closely at the Tree Structure
Provided that a tree or shrub is a good candidate for winter pruning, one of the benefits of doing pruning in the dormant season is that you can clearly see the structure of the tree or shrub. Without leaves, crossing limbs, twisted branches, or weak branch crotches joining the main stem are easier to identify.
Thin out crowded areas, remove suckers and watersprouts, and you’ll be well on the way to having an attractively shaped tree ready for spring growth. If your tree needs heavy pruning, focus on the worst offenders and do more pruning later. The general rule of thumb is to never remove more than about a quarter of the branches at a time.
6. Sharpen Your Pruners
If you've got a brand new set of pruning shears, you can skip this step. But for older pruners, it’s worth the effort to clean them up, inspect them, and sharpen them if necessary. Sharp pruning shears are much easier to work with and make cleaner cuts. Sharpening most pruning shears is easy and only takes a few minutes.
Here are a few hints that help you determine whether your pruners need sharpening:
- There are visible dents or nicks on the blade.
- The cutting edge (the actual edge, not the bevel) of the blade reflects light and looks dull like a butter knife.
- Cuts aren’t clean and sometimes leave a torn or ripped edge.
- The pruners require more force to complete ordinary cuts.
- The blade is rusty.
7. Disinfect Your Tools
Bacteria, viruses, or fungal spores, which are invisible to the naked eye, can be spread from one plant to another via pruning tools. Not all plant pathogens are killed in the winter cold, and pruning creates a wound that provides any pathogens on your pruners a perfect introduction to the plant. Sanitizing pruning tools is a simple way to prevent disease transmission.
To avoid giving pathogens a free ride, sanitize your pruners between plants. A small spray bottle filled with 70% or stronger rubbing alcohol (isopropyl alcohol) is easy to use and carry. Just wipe or spray your tools; they don't need to be soaked. Bleach solutions also work but are more cumbersome and require a several-minute soak time. Bleach may also cause tools to rust prematurely if it isn’t rinsed off properly, and drips stain your clothes.
