I am in zone 8b/9a, southern California high desert. Our winters are pretty frigid, temps drop into the teens quite often and we get snow a few times a year usually (sometimes heavy). Lots of frost here. Besides lots of sempervivum, jovibarba, and opuntia, I have some lithops that manage quite well so long as they are bone dry and I bring them in on the coldest nights just to be safe. They just get plunked in my cold garage overnight and do fine. My aloe veras and 10 year old aloe ferox live outside all year in their pots, but come up onto my covered patio in winter and get covered with old blankets at night. One of my aloe veras was once forgotten outside on a frosty night unprotected and got a pretty good frost burn on a few leaves but survived. My adenium obesum spend the winter in my unheated garage. My echeverias and graptoverias overwinter in there as well even though it sometimes feels like an ice box. Surprising how many heat loving plants (my lemongrasses and lemon verbenas overwinter in my garage as well) can take low temps but I suspect that if I had them unprotected and in-ground, they would be toast after one hard frost.
