Fall is often considered a good time for planting, but experts caution against pruning woody plants during this season. As autumn progresses, woody plants begin to move nutrients from their leaves and branches down into their roots to prepare for winter and support spring growth. Pruning at this time can disrupt this process by encouraging new growth that is vulnerable to frost and cold damage.
Another concern with fall pruning is the increased risk of fungal diseases. The decaying conditions typical of fall create an environment where fungi thrive, and making cuts on trees or shrubs provides entry points for these pathogens. Insects are also seeking shelter for winter, and open wounds from pruning can attract pests. Cooler temperatures slow down the healing of plant tissue, leaving wounds exposed for longer periods.
Pruning in late fall also removes nutrients that would otherwise be stored in the roots over winter, potentially impacting tree health in the following growing season. “Pruning is also a stressor for the tree. In the current drought conditions, when woody plants are already under stress, pruning can severely impact tree resilience and reduce vigor in the season to come,” according to guidance from University of New Hampshire Extension.
There are exceptions: it is always acceptable to remove dead, damaged, or diseased branches—referred to as the “3 D’s.” Removing deadwood does not harm the tree if live tissue is not cut. Damaged branches should be removed only when necessary for safety, with major pruning postponed until dormancy. For diseased branches, keep wounds small and use sanitized tools to prevent spreading disease.
The recommended period for most pruning begins once woody plants are fully dormant, typically after the new year in New Hampshire due to recent weather patterns. Late dormant season is ideal because pathogen levels and insect activity are low and sap flow has stopped. For spring-blooming plants, prune after flowering so they have a full summer to recover and bloom well the following year.
The University of New Hampshire Extension notes that March marks the start of pruning season for local gardeners and orchardists. More information about demonstration schedules can be found on their website at https://extension.unh.edu/resource/pruning-trees-shrubs.
