Stella Cherry not flowering

I bought two bare cherry trees last year from a garden centre. They are in pots in a north facing garden; the pots back onto an easterly fence line.  You can see the Morello cooking cherry on the left looking very promising however, the Stella eating cherry on the right only had a few branches on the right hand side in flower so I presume I will get very little fruit from it? Can anyone tell me why this is please?