By Wharfm
United Kingdom 
Why doesn't my hydrangea flower?
Planted in the ground with other bushes which are fine, the hydrangea is healthy with good leaves but never flowers.
The plant has been in the same position for 15 years but not flowered once.
7 Aug, 2014
Answers
That's what I thought too. Of course it would grow better the right way up...(sorry!)
When pruning mophead hydrangeas you wait until about March or April and cut off the dead flower heads. It will not flower on growth made in the current year. Most hydrangeas the age of yours would be about five feet tall by now. You can't keep it the small compact size it was when you bought it.
7 Aug, 2014
think maybe you are pruning off the new flower buds every year it looks very compact so I assume you have trimmed it.
7 Aug, 2014