Pruning Hydrangeas (with proof)
I’m so, so tired of arguing with people about when to prune hydrangeas. There are so many blogs, YouTube videos, and Facebook posts on the subject that my head spins.
And then there are the neighbors. The neighbors that cross the street to tell me that they definitely prune _______ hydrangeas during the ________.
Don’t know the difference between new wood and old wood?!?! You might as well put your house up for sale! I’m serious. Pack your bags. You don’t deserve hydrangeas!
My response to the insane amount of planting “information” on social media.
Now, I totally get the irony of me contributing the 823,748,234th blog post on the subject, but here’s my unique value proposition: my information is affirmed by academic sources: Cornell Cooperative Extension, the Penn State Extension, and the University of Minnesota Extension: all Zone 5 agricultural research powerhouses that have all the facts and none of the clickbait.
Identifying Old and New Wood
Old Wood: Growth from the previous season. Buds for the current year’s flowers develop on this wood (aka last years stems; woody and textured)
New Wood: Growth from the current season. For some varieties, flowers form on this year's growth (aka this years new growth; green and smooth)
Understanding Hydrangea Varieties
Before you start pruning, it’s essential to know which type of hydrangea you have. Different varieties require different pruning techniques and timing.
Hydrangea arborescens (Smooth Hydrangea)
When to Prune: Late winter to early spring
Pruning Tips: This variety blooms on new wood, so it’s best to prune back the stems to about 18 inches. This encourages robust new growth and abundant blooms.
Hydrangea macrophylla (Bigleaf Hydrangea)
When to Prune: Shortly after blooming in mid-summer
Pruning Tips: Bigleaf hydrangeas bloom on old wood. Prune immediately after flowering by cutting back stems to just above a pair of buds.
Hydrangea quercifolia (Oakleaf Hydrangea)
When to Prune: After flowering, in late summer or early fall
Pruning Tips: Prune lightly to shape the plant and remove any dead or damaged wood.
Hydrangea paniculata (Panicle Hydrangea)
When to Prune: Late winter or early spring
Pruning Tips: Panicle hydrangeas bloom on new wood, so they can be pruned back hard to encourage vigorous growth.
Hydrangea serrata (Mountain Hydrangea)
When to Prune: After flowering, in midsummer
Pruning Tips: Like bigleaf hydrangeas, this variety blooms on old wood, so prune after blooms fade.
Hydrangea anomala subsp. petiolaris (Climbing Hydrangea)
When to Prune: Late winter or early spring
Pruning Tips: Prune to control size and remove any dead or crossing branches. This variety flowers on old wood, so avoid heavy pruning.
Conclusion
What’s that? Did Susan cross the street while you were reading this to tell you I’m wrong?! Well Susan here’s proof, proof, and more proof.
