Now that winter is only two weeks away, and many deciduous plants are defoliating and dormant, it may seem as if there will be less work to do in the garden. After all, not much is growing. The funny thing is that this is the best time to sneak up on some of them, and prune them while they are sleeping. Depending on what is in the garden, winter can be just as busy as any other season.
There are a few things that should most certainly not be pruned in winter. Maples and birches should either be pruned before or after winter. They bleed profusely if pruned in winter. Plants that bloom in winter or early spring should be pruned after they have finished blooming. Pruning forsythias, flowering cherries and flowering crabapples earlier will remove much of the blooming stems.
Deciduous fruit trees are of course an exception to that rule. They require annual winter pruning so that they to do not produce too much fruit. Excessive fruit is of inferior quality, and can break limbs. It is acceptable when pruning fruit trees to leave a few unpruned stems to cut and bring in later, as long as they are not forgotten. They can be less refined alternatives to flowering cherries.
Once we determine what should not be pruned in winter, it is easier to see that most deciduous plants should be pruned while bare in winter. Elm, oak, poplar, willow, mulberry, pistache, gingko, crepe myrtle and most popular deciduous trees are sound asleep and unaware of what might happen to them for the next few months. They would be pleased to wake already pruned next spring.
Some evergreen plants should probably be pruned as well. Tristania, redwood, podocarpus, Carolina cherry, bottlebrush and the various eucalypti would prefer to be pruned while the weather is cool. Conifers bleed less this time of year; and pine and cypress are less susceptible to pathogens that are attracted to wounds during warm weather. Avocados and citrus, particularly lemons, should not be pruned in winter, because pruning stimulates new growth which is more sensitive to frost.