Can summer pruning damage hydrangeas?
Written by
Paul Reynolds
Reviewed by
Prof. Charles Hartman, Ph.D.Summer pruning must be executed with precision to avoid bud damage on hydrangeas located on old wood. Most reblooming hybrids, such as Endless Summer, will benefit from deadheading once in bloom, but traditional mophead hydrangea varieties lose next season's flowers if pruned after the end of July. I once salvaged a client's oakleaf hydrangea that was butchered in August, and it took that plant more than two years to bloom again.
Safe Practices
- Deadhead rebloomers above first set of healthy leaves
- Sterilize tools with 70% alcohol between plants
- Limit cuts to spent blooms only after June 30
Risks to Avoid
- Cutting live stems on old wood varieties
- Leaving ragged cuts that invite powdery mildew
- Pruning during drought stress or heatwaves
A client's panicle hydrangea was pruned in July and the stems were weak, breaking under the weight of the bloom. We staked the flowering stems and avoided cuts throughout the summer and now the blooms are sturdy and upright. It is best to use sterilized bypass pruners when working to avoid bacterial infections that are often present during the summer heat. Clean tools are just as important as timing when doing your work.
Read the full article: When to Prune Hydrangeas: A Step-by-Step Guide
