I have several hydrangeas in different gardens around the house. They are different colors and maybe different types. All of them bloomed beautifully the first few years after being planted but they have gradually all stopped blooming. I didn’t get any flowers this year. The foliage is beautiful and healthy looking but no flowers. Why?
I've done some additional research and came across this article. http://ucanr.edu/datastoreFiles/268-86.pdf
It has more detail on pruning and describes rejuvenating older hydrangeas by removing 1/3 of the oldest branches to the ground annually. This is a common technique for keeping shrubs full of young wood which blooms better than old wood. However, I had not seen it mentioned before with regards to hydrangeas.
You aren't the only one who has had this problem. The chief reasons for not blooming are improper pruning, too much shade and warm early spring followed by a hard freeze. Where I live, we had balmy weather in March this year followed in April by 2 nights of 20F. It zapped hydrangeas and magnolias something fierce. If you are using a high nitrogen fertilizer, stop. Most hydrangeas don't need fertilization unless a soil test shows deficiencies or they are grown in pots. Too much nitrogen spurs green growth at the expense of flower development.