Earthenware (low-fire) pots are always more likely to break in freezing temps because they will absorb and hold moisture. Stoneware, (which is most of what I make), is less subject to climate extremes.
Insert technical jargon here....or better yet, ask your son if he's been told what "vitrify" means yet! It's one of the FAQs I'm in the process of developing.
I would love to see pix of people's succulents in pots in a forum! I always try to get great ideas at the shows we have here, but it's often the same plants in the same pots displayed at each event.
