Hydrangea not leafing

Hi all,
I'm after some advice for my beautiful (was!) Hydrangea. Its been in a large pot and has been fabulous the last 2 years. Now hardly producing any leaves and I've no idea where to go with this. Its alive as has green centred branches but I'm thinking I may have pruned too soon last year? If I cut back in December/ Jan would that make such a drastic difference? Ive added some bone meal a few weeks ago and watered but no difference..do you think planting out would benefit though it's not pot bound?
Pic attached of what it was like last year

 

Is it in ericaceous compost?

 

Thanks both. Yes its in ericaceous compost hence the beautiful blue colour last year! I have 3 other hydrangea that have been fully leaved for many weeks now and indeed this is trying but not getting anywhere. Is it true that hydrangea have shallow roots? If so, I have the perfect garden spot that it may be happy in!

 

Two of mine have good growth, the third has just appeared above ground having been ground into the ground by a tracked cherry picker last autumn.
So don't give up yet.
Remember hydrangeas flower on wood formed the previous year, so hard pruning risks losing the summers flowers.

 

Hope it’s ok to jump onto this thread, I have a Hydrangea Macropylla with green/ burgundy leaves that I bought as a bargain from a garden centre, quite big in a 12L pot. Planted it the end of March when it was a mass of sticks and a few new shoots. It now has an incredible amount of leaves and think it will flower around July - see photo below
There’s a few new green shoots among lots of woody older growth - should I be cutting out some of the wood to get a a bit of air and light down at the base ? If I did this there would still be plenty on it. I know I sound like a real novice, should I cut back the tallest stems as well as crossed stems to give it a better shape ? I did some pruning before all the leaves grew but I don’t think I took enough out
The plant is near a fence and has partial shade /sun

 

Morning Brennabee
You're asking the wrong person! But judging by the photo, I wouldn't do anything as its clearly happy as is. I always feed mine once they start flowering and just leave for the season but others may tell otherwise. I can only think that the issue with mine is that I cut it back too harshly this winter as its not produced any more leaves than a few at the base. I'm hoping that feeding and nurturing again will bring it back to its former glory next year. It was a real show stopper! Good luck with yours