Many gardeners are pruning trees and shrubs this time of year. One shrub that often confounds people is the hydrangea. The reason for the confusion is different species of hydrangeas are pruned at different times. So, let's do a quick hydrangea pruning 101.
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First, remember when your hydrangeas bloom. If they bloom mid to late summer they are flowering on the new wood. This means the new stems that grow this spring will terminate in a flower. Arborescens hydrangeas such as 'Annabelle' and 'Invincibelle Spirit' and Panicle hydrangeas such as 'Pee Gee' and 'Quick Fire' fall in this category. Cut side branches back to a main branch or trunk, removing crowded shoots and suckers to open up the shrub.
If your hydrangeas bloom in early to mid summer, they probably flower on old wood. This means the flower buds formed on the plant the previous summer and fall similar to how lilacs bloom. The mophead hydrangeas, such as 'Nikko Blue', lacecap hydrangea, climbing hydrangea and oak leaf hydrangea fall in this category. Prune these after flowering to shape the plant. A third group, made famous by the 'Endless Summer' blue hydrangea, blooms in early summer on old wood and in late summer on new wood. Newer varieties such as 'Bloomstruck', 'Blue Enchantress' and 'Everlasting Revolution' are more reliable repeat bloomers. Prune these after the first flush of flowers.
In colder parts of the state, if you have trouble getting these blue hydrangeas to bloom mound a 1- to 2-foot deep layer of wood or bark chips over the plant in early December to protect overwintering buds and branches.
