Pruning

Asked January 27, 2020, 11:59 AM EST

Is it best to (dormant) prune trees when it is not raining? If so, how much time are we looking at insofar the wound sealing up to adequately protect itself from fungi? Needless to say, rain is an issue here in the Pacific Northwest!

Clackamas County Oregon

7 Responses

Thank you for your question. What species of tree are you asking about? In general, most trees should be pruned while dormant (no leaves). And rain isn’t so much of a problem as freezing weather. But, without knowing whether you are asking about fruit trees, deciduous trees, or conifers, we cannot give you reliable data. More info, please? Thanks!

Thank you for your response. The trees that I am going to prune are all deciduous: Weeping Willow, Red Alder, Ash, Giant Empress, Red Oak, Sweet Gum. I look forward to hearing back from you! Thank you!

Thank you for your response. The trees that I am going to prune are all deciduous: Weeping Willow, Red Alder, Ash, Giant Empress, Red Oak, Sweet Gum. I look forward to hearing back from you! Thank you!

Thank you for clarifying. Here is a comprehensive Extension article on pruning: https://extension.oregonstate.edu/crop-production/fruit-trees/tree-pruning-basics A cold snap is forecast, so you might want to wait a few days until the risk of freezing has passed. Good luck!

Thank you for sending the link. There is nothing in it which addresses the issue of rain and pruning but I did find this from the Sacramento Orchards website:
"Ideally, avoid pruning prior to predictions of significant extended rainy periods. Figure 1 shows what can happen when pruning cuts are made just prior to a rain event. When pruning is necessary such as train-ing young trees or removing diseased limbs, try to avoid the practice when wet conditions are predicted in the two week forecast. Whatever you do, don’t mix pruning and rain." I'll contact one of my arborists and hopefully they can weigh in on advise for the Pacific Northwest Many thanks for reaching out!


I searched WSU an OSU publications for rain issues. Trees bearing fruit and nuts are more susceptible to some of these issues. None addressed it. If we wait for no rain to prune, it may be June!

Re: evergreens: "Avoid pruning diseased trees in wet weather. Both the plants and the air should be dry for several days before pruning and until the pruned debris is burned. An extended period of dry weather during late summer is an example of a good time to prune diseased branches. The risk of spreading disease spores through tools or the careless handling of infected material is greatly decreased during dry weather." (https://www.extension.uidaho.edu/publishing/pdf/BUL/BUL0644.pdf)

The following Master Gardener blog advises to "wait until the rain stops" in the title, and then never mentions the issue in the article: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=23014