They are tender plants, Amanda, and frost kills them. Most people treat them as annuals and grow new ones each year. I have a pot of them in the greenhouse overwintering, but I really haven't got the space to keep many.

Thanks for your comment. That's what I thought although don't have much room to keep them safe during winter. But think I will get some anyway as I do love them and maybe just keep a few in the conservatory over winter maybe.

I do too - I'll be growing more this year. :-) Good luck with yours.