I just put up a post from 2 days ago showing my outdoor lady that is a little over 60 days old growing outside, after a 28* frost. Cannabis is a hardy plant, as long as they have the right nutrients and water they can take an extremely wide temperature variation. Think of some of the places that have grown it for hundreds even thousands of years. The mountains of Afghanistan for instance just before harvest season may get frost in the morning and up to 90* by noon. Some of the best Indicas have Afghani genes in them. Even the Sativas can survive a mild frost.