Thank you all for the replies. I am going to dig the rhubard out of the pot
and put it in some new vine weevil free compost.

The reason it is grown in a pot is as we have no room for it in the garden
and the boyfriend and I are currently looking for our own place so its kind
of a temporary home for it. Its been moved into the sun as over winter I
had it in a place that was more protected from getting too wet and cold, so
its now moving into the sun to get a good growth on so I can eat some yummy
rhubard