Huernia is a delightful and odd species to grow. There are many different hybrids available that have very unique flowers some of which may be a bit stinky. Huernia is prone to overwatering. I like to use cactus soil for root growth and gravel to keep the plant standing upward ( some have long branches) Use a time release fertilizer and keep in bright shade or early morning dappled sun from the shade of a tree. Take indoors if temperature falls below 50 F although I have heard they may take colder weather if kept dry.
Ruby Trumpet