Deadheading Endless Summer Twist-n-Shout hydrangeas
We have six of these Endless Summer Twist-n-Shout hydrangeas and they bloomed satisfactorily their first two years, this being the third. This spring the branches are covered with what appear to be dead buds that emerged during a warm spell. As of now, early May, the shrubs aren't doing much, but all six have at least one promising-looking green bud at the base of the plant. The dead-looking buds continue to look dead! In spring 2019 they all regenerated by sending up new stems from the ground, and the old ones finally disintegrated. The same seems to be happening this season. Some of the old stems are green at the base, but that doesn't go very high. So should we just prune, i.e., cut off all the old wood, perhaps leaving what looks green and living? Will that help the plants, or should we leave them alone?
Ramsey County Minnesota
Thanks for your question. Good news, I wouldn’t worry too much about your hydrangeas.
Endless Summers are a unique variety. Most hydrangea species can be categorized as those that bloom on old wood (last year’s growth) or those that bloom on new wood (current year’s spring growth). Those that bloom on old wood tend to flower earlier in the season (late spring/early summer), whereas those that bloom on new wood tend to flower later in the season (mid-summer/late summer). Endless Summer hydrangeas are one of the unique varieties that bloom on both old and new wood, therefore they can bloom throughout the summer season (hence “Endless Summer”). An exception to this is when the buds on old wood are killed or pruned off—then you won’t see flowers until later in the season.
The branches you identified dead buds on were likely damaged during the last late frost we had. So while you may not see many flowers early in the season, there should be some later on in the summer as new-wood branches come into bloom.
When it comes to pruning, hydrangeas tend to be pretty low-maintenance. Especially young shrubs like yours—they can typically just be left alone. When the shrub gets older and you do choose to prune, usually you can limit your pruning to removing spent flower heads and dead branches. To identify a dead branch, scrape off some bark from a branch you’re concerned about with your fingernail. If the tissue you uncover is green, the branch is still alive. If the underlying tissue is brown or dark, then the branch is dead.
Hope you get to enjoy some late season blooms this year—let us know if you run into any other issues.