I think they are best if left in pots. I myself have also lifted them from pots after they have died down. Keep them regularly fed until they are died down fully. Then when their leaves are gone, have them up and store somewhere dry in a paper bag. I stored mine in my living room cupboard all last summer for an experiment. They replanted in the autumn and have flowered perfectly for me this spring. A shed is more the usual place.

If you don't want to leave them in the pots once they have died back completely plant in the open ground where you would like them to flower next year.

thanks once again moon grow

thanks jonathan ha