When asked the question, “When is a good time to prune?”, I usually respond with, “Depends on the tree species, current health/past disease history, current weather/season of the year and type of pruning being considered.” (I used to try and be brief, giving 5 word answers until it was obvious that approach led to many more questions than answers.) That’s my way of giving a background to the “when to prune”  issue and letting it be known I need to get some answers of my own in order to accurately answer the question.

The final answer may be simple or complex depending on the tree’s biology, purpose, current and past health, season of the year and current weather.

For example, if I knew someone wanted to prune a Douglas Fir tree, I would ask them what they hoped to achieve from the pruning. Tree health, view enhancement, screening protection, aestetics, building clearance?

Removing dead wood can be done anytime. Removing 10-20% of the canopy would require knowing the time of year and current weather, the overall health and age of the tree and if summer irrigation is present. Depending on the above, there may be some more questions regarding soils, site exposure, type and health of nearby trees, etc.

Late October-March is the best all around time to prune Douglas Fir trees in Southwest Washington, as well as most other conifers. Soil moisture is favorable for bark beetle defense and egg laying is not active.

In the case of when is the best time to prune a fruiting or flowering tree (such as apple or crabapple)  I ask how important fruit and flowers are and the acceptible level of maintenance .

However, maples, apples, cherries, plums, however, are best pruned July-October, as are most other deciduous trees. Some varieties of Japanese Maples can be ready to prune in June if the weather is fairly dry.