Old wood hydrangea, like Oak Leaf, should be pruned AFTER blooming, if at all. During the dormant season, they can be deadheaded if they were not deadheaded after blooming. And of course, the 4 D's can be done at any time of year. The 4D's may be more obvious when these shrubs have no leaves..
Check here to Link to Old Wood Hydrangea Video
Prune Like a Pro_Hydrangeas-old wood.pdf
Check out the Knox County Master Gardeners YouTube Dashboard
for additional presentation videos as they become available
LINK to KCMG Dashboard
