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Pruning hydrangeas is actually quite simple once you know what type of hydrangea is growing in your garden. Common hydrangeas belong to four different species, but there are five common types, each with slightly different pruning requirements. Before you reach for the pruners, determine which species you’re growing. (Need advice on putting your hydrangeas to bed for the winter? We’ve got you covered.)
Old wood vs new wood
“Old wood” means that buds are formed for next year’s bloom at the end of the current growing season on stems produced during the previous summer. Typically pruned after flowering or in early spring to encourage new flower buds on old stems.
“New wood” means stems that have emerged during the current growing season. Buds are formed on this new growth in the current growing season.Typically pruned in late winter or in early spring to encourage new stems.
Big-Leaf/Mophead/French Hydrangeas (H. macrophylla)
Remove up to one-third of the total stems each season, starting with the weakest shoots, both old and new ones. Cut these right down to the ground and remove. What’s left are a combination of old productive wood and strong new stems that will flower next season. Shown: Nikko Blue Hydrangea
Smooth Hydrangeas (H. arborescens)
Older varieties such as the classic Annabelle can become floppy and unruly. Newer varieties such as Seaside Serenade® Bar Harbor Hydrangea have been bred to be more compact. Either way, cut back to the ground (don’t be afraid – cut).
Panicle Hydrangeas (H. paniculata)
Pruning may not be needed every season. If they seem overgrown or floppy, especially after a hard rain, pruning will tune them up. Take off up to 30%-50% of the old growth, before they leaf out, to create a roundish shape. Shown: Angel’s Blush® Hydrangea
Oakleaf Hydrangea (H. quercifolia)
Oakleaf hydrangeas want to be left alone to do their thing. They require very little pruning; limit to removal of dead or broken branches as needed. You can improve the shape of the plant by pruning in summer after it finishes flowering. Shown: Snow Queen Oakleaf Hydrangea
These bloom on growth from the current year as well as previous years. The “old wood” buds provide early season color, while blooms forming on current season growth flower later, lasting through the end of the season. All they really need is deadheading spent flowers and pruning out dead or weak stems. Shown: Seaside Serenade® Fire Island Reblooming Hydrangea
Hydrangeas in Winter