Pruning my Vanilla Strawberry Hydrangeas
I have beautiful vanilla strawberry hydrangeas. They are 2-3 years old and when they bloom, they are still very heavy and tend to fall over. I staked them this year (will do a better job next year if need be) but I am not sure how to prune them to encourage the stalks to grow stronger. I know I prune them at the end of winter, but can't figur out if I cut the whole things down or trim the blooms and let the new blooms grow on the established branches. Thank you so much for any guidance! Jane M.
Multnomah County Oregon
Thanks for your question about pruning your hydrangeas, Jane. The short answer (derived from an Extension handout) is: Hydrangea paniculata-very hardy shrubs with large cone-shaped flowers from late summer to fall. Flowers usually age to pink shades. They are sun-tolerant and bloom on new growth so they can be pruned in spring without diminishing blooms.
Having said that, however, one of the problems with these (as well as some other very hardy hydrangeas) is that the blooms are so heavy that they can become weighted down with rain (and eventually snow), so it's best to remove the spent blooms as they lose their color. And you can remove all of them when it begins to be cold. Otherwise, the weight of the blooms may break off the stems in cuts that aren't helpful to the shrub.
Here's a link to an Extension article about pruning ornamental trees and shrubs, generally, which should give you some advice about pruning cuts and techniques. Hope it is helpful. Good luck!