You can prune a tree anytime of the year. Some say it’s best to prune a tree “any time the tools are sharp.” However, understanding how your tree will respond to pruning will help you make the best decisions for your tree. Generally speaking, the following guidelines apply:
- Broken and dead branches as well as root suckers can and should be pruned at any time of year
- Because most trees in Portland experience seasonal dormancy, pruning live branches during the winter months encourages vigorous new growth in the spring without depriving the tree of actively photosynthesizing tissues
- Limited pruning is okay in the summer. Keep in mind that pruning during the growing season removes leaf surface that is manufacturing food for next year’s growth. Light pruning will have little impact on future growth, but heavy pruning may slow or dwarf your tree’s growth
- Avoid pruning in the spring to prevent damage to delicate young leaves and buds
The City of Portland has a ban on pruning elm trees during the growing season (from April 15 to October 15). Pruning cuts can attract the elm bark beetle, which is the major vector of Dutch elm disease. Click here to learn more about Dutch elm disease.
Hands-on tree pruning classes are offered by Urban Forestry at different times of the year. View the Urban Forestry Events Calendar for upcoming workshops.