My parents have a very old Cereus peruvianus. While they usually bring it in during the winter, it was left outside for most of last winter and faired well (on a porch.) I was really suprised the thing didnt turn to mush when it frooze, I guess it had lots of protection. BTW, they live in Augusta Ga. zone 8a, a little cooler than Charleston. Good Luck !! Michael M.

Succulents seem to survive the SE in either of two ways.
1. Planted in raised bed of very fast draining stone and sand.
2. Planted in hard red clay that no moisture can penetrate.

The worst weather is freezing precipitation that stays in the soil a long time. I don't think you get that in Charleston, SC.