Acer Palmatum Mikawa Yatsabusa

I bought a very small acer mikawa yatsabusa (about 4 ins high) about 3 years ago. I had it in a pot for 2 years & it didnt grow very well, so last year I transferred into the garden, in a well sheltered shady spot, but it just put on a few leaves & then shed them early. It seems to be doing the same this year. It seems to be not growing any at all, it is still the same height as it was 3 years ago. Is it a slow grower?. I have quite a few other different acers of varying ages both in pots & in the garden & they are all doing very well. Does this one need special attention?
PS.I have given it the odd weak solution of ericaceous plant food.
Thanks

 

It sounds to me as though it might be root bound?
Tease out the roots, make sure it is in a well drained spot and then leave it alone

 

Thanks for your reply whis4ey, I'm afraid to disturb it now, it is really very delicate, do you think it would do it harm to tease out the roots now? I think I would rather leave it until next spring & do it then.

 

If the roots haven't ventured out into the surrounding soil then no harm whatsoever can be done by digging it up
When you say that it is 'not growing any at all' I am assuming that to be the case
At the end of the day, the choice is yours