My bush has not bloomed in 20 years?Looks nice but does not bloom.
20 YEARS!?!?!?! No blooms at all? Is it planted out of zone? What variety of hydrangea is this? Do you know the name?
Is it a macrophylla hydrangea? Your zone is cold enough that the buds may be freezing--or late-spring warm-up periods alternating with late-freezes may be taking those buds. I'm assuming you are about in Zone 6. Macrophylla hydrangeas often don't bloom well in Zone 6--I no longer even try to get them to bloom. My neighbor must have about 6-8 of them--they have never bloomed in the 6-8 years she has had them. We are in Zone 6 also.
What I do instead is plant Annabelle hydrangea in semi-shady spots and some paniculata hydrangeas (like Pinky Winky) in sunshiny spots. They are all surefire--you'd have no problem with them not blooming.