Winterthur Garden Blog

A question we often hear this time of year is, “When should I prune my spring flowering shrubs?” Azaleas and forsythia, for example, can take us by surprise in spring by how much they have grown. You may need to prune your shrubs to restore their shape or to reclaim a path or part of a bed. In general, the correct time to prune these shrubs is right after flowering. Prune by removing weak or damaged wood and by cutting flowering branches back to areas of vigorous growth. Be sure to keep an eye on the shape and habit of the plant by stepping back and reviewing your work frequently. By pruning right after flowering, you allow the plants to develop replacement shoots that will mature and flower the next season. If you delay pruning too late into the growing season, or into the winter, new shoots won’t develop or they will not ripen enough to produce flowers. This rule of thumb can be used as a general guide for azaleas, forsythia, corylopsis, flowering quince, lilacs, and most other shrubs that flower in spring.