It looks as if its fighting for space in that pot - there's something else in there with it, is there? Have you tried planting it directly in the ground?

It's possible that the soil is too acidic, peat moss is quite acid. Ferns like something alkaline to neutral & humus rich. Pine needles are more acidic too so don't plant ferns under them generally.
I'd tip them out, shake off the soil & repot in some multi-purpose compost with grit added for drainage. Maybe put in dappled shade rather than a really dark area

Thanks I'll try it in the ground with all the advice given

Do you know what the other plants in the pot are?
Is the fern supposed to be evergreen? If it isn't it should recover well without the competition.
In your original question didn't you ask for other suggestions or your shady corner? Do you still want those too and if so could we have a pic of the corner in question?

Yes Steragram it's supposed to be evergreen and there's a lot of Crocosmia that has multiplied over the last 2 yrs. I'll take it out and clear everything
from it.