I am in zone 7 in the Seattle, US area and I would plant it. Just plant something like half and save the rest if you want to be on the safe side. I have bee balm (same family) and the stuff grows like mad. If you get one of the little guys going you'll be set for divisions a plenty.

hello, thanks for your reply.I did exactly what you suggested.They have grown really fast and I am looking forward to planting them out and seeing them flower.Ive never grown them before.Thanks