In Portland Oregon the Zone map goes back and forth between zone 8b and 9a. I put Charles in the ground this spring and was wondering how hardy they actually are. I've heard many conflicting stories of hardiness, so I'm confused on just how hardy they are. I never have been able to get them to overwinter in my garage because I forget about them. I can successfully grow oleanders and grivelleas if that helps. I'm on a south facing slope which keeps me at least 5 degrees warmer than the rest of Portland.
Thanks
Nathan