When and how you prune your hydrangea can mean multitudes of glorious blooms or
. . . no blooms at all!
The trick is in knowing which of the five different types of hydrangea you have. So, when you plant, be sure to save the label! That way, when it comes time to prune, you can do it correctly without sacrificing the beautiful blooms. Keep in mind that certain types of H. macrophylla may not ever bloom for you if they are not "bloom hardy" in your area.
Tips for Pruning Hydrangeas
Even though there are five different types of hydrangea, each of these falls into one of two pruning groups, based mostly on whether they bloom on wood produced in the current year or wood produced in the previous year.
Pruning Group 1
This group includes the species that bloom on old wood - Hydrangea macrophylla (aka. mophead, lacecap, bigleaf, hortensia, or florist hydrangea) and Hydrangea quercifolia (oakleaf hydrangea).
- Flower buds of these hydrangea are formed in August through October depending on the species.
- These hydrangea do not necessarily require annual pruning.
- Prune these, if needed, right as the flowers begin to fade usually in mid-summer.
- To be safe, DO NOT prune them after July.
- For mature established shrubs, the regular removal of 20% of the oldest stems (cut at soil level) will keep the plant vigorous and blooming well with larger flowers. Do this in the spring.
- Deadheading or removing the spent blooms can be done continuously through the season.
- Some evidence indicates that leaving old blooms on the plant through the winter may help protect the tender buds below them. In colder areas, consider leaving them and removing them in the spring after the shrub breaks dormancy.
- Dead and damaged stems should be removed whenever they are noticed.
- Oakleaf hydrangea does not require annual pruning and should be pruned mainly to remove dead or damaged stems or to limit its height.
- Watch Mark's video tip on "Why Hydrangeas Don't Flower"
Pruning Group 2
This group includes the species that bloom on new wood - Hydrangea arborescens (smooth hydrangea, includes 'Annabelle'), Hydrangea paniculata (Panicle or PeeGee Hydrangea), Hydrangea anomala ssp. petiolaris (Climbing Hydrangea), and reblooming varieties of H. macrophylla such as 'Endless Summer'.
- These species of hydrangea produce flower buds on the current season's growth about one or two months before they bloom.
- In general, these can be pruned after they finish blooming up until they begin producing flower buds in the spring; i.e., fall, winter, or early spring.
- H. paniculata does not require annual pruning except to remove wayward branches and stems. This species can be developed into a single or multi-stemmed tree by maintaining just the desired number of stems/trunks and pruning out all but the upper branches. It can also be cut back to 18" - 24" from the ground to rejuvenate the shrub and to limit its size. Watch Mark's video tip on training Hydrangea 'Tardiva' into tree form.
- H. arborescens cultivars such as 'Annabelle' can be pruned to the ground in the fall or late winter before active growth begins in spring. This promotes large flowers! If your Annabelle hydrangea tends to flop over from the weight of the flowers, try pruning to 18" - 24" rather than cutting them to the ground. This will allow the stems to thicken and provide stronger support for the large blooms. Watch Mark's video tip on pruning Hydrangea 'Annabelle'.
- Reblooming types such as 'Endless Summer' can be deadheaded to encourage continuous bloom.
- Climbing hydrangea require little pruning except to limit its growth to the space you have. Early spring or in summer after flowering is the best time to prune this species.
- Dead or damaged stems should be removed whenever they are noticed.