It has been said that the best time to prune is whenever your pruners are sharp. It’s not bad advice. We can get by with pruning about any time of the year. There is, however, better times for pruning than others. Fall is typically not that time. Let me explain…

Woody plants move sugars and other materials from the leaves to storage places in the woody portions of the plant just prior to leaf fall. It’s in our best interest to maximize those stored energy reserves for the health of the tree. Pruning now may reduce those reserves.

We also want to make sure plants are hardy going in to winter. According to Penn State University’s Dr. Rich Marini “Based on everything that has been published we can conclude that woody plants do not attain maximum cold hardiness when they are pruned in the fall”.

There are always exceptions, though. According to Marini, trees tend to be more affected more by heavy pruning than light pruning. In other words, we can probably get by with some light pruning unless we see a sharp drop in temperature before plants are completely hardened off. Marginally hardy plants are more susceptible to winter damage, especially if pruned in the fall. Bottom line: though light pruning and removal of dead wood are fine this time of year, you may want to delay severe pruning until spring.

What is ‘light’ pruning? If 10 percent or less of the plant is removed (not including dead wood), pruning would be considered light. CAUTION: even light pruning of spring-blooming shrubs such as lilac and forsythia will reduce flowers for next year. We normally recommend that spring-bloomers be pruned after flowering