I wait until they have died back completely, say October, and then plant out.

Thank you Bulba..I will do that ..

I often leave them in pots frost free/shed/etc and start them into growth and then plant out in late spring. but either way it makes little difference to them.

Thanks Sbg..I left mine in pots last year,covered with old perspex shed window panes :o) ..no problem...It seems either way will be ok,so now I have a choice...