Have always wondered about this, nice to read all the replies. We live in the frost free climate of Port Elizabeth, South Africa. We didn't get round to digging up our runner beans last year and as spring arrived they started shooting, so we left them, watered and fertilised them with worm wee. We also planted new seeds. It's Christmas day and we are enjoying a lovely addition to our normal English Christmas dinner - freshley picked succulent runner beans from the overwintered roots. These are a couple of weeks ahead of the newly planted ones. But try growing parsnips - forget it, we have to try to get imported ones !!!!