I have had hoyas for almost a decade. I have most of them in terracotta that has been glazed on the outside. A couple were glazed inside as well but all of them have a drainage hole. For mine that seems to be most important. Most of their life I lived in zone 9a. But I've moved and believe I'm now in 9b but very close to the Indian river. We've been here about a year and they are perfectly happy but I believe its because both homes the porch they are sitting in is north facing, all of these have bloomed at some point.
That being said one of them has lived in a plastic pot its whole life. It has lived but never bloomed and seems to go through more changes through the year than the others, I dont think its happy but there is always another chore that keeps me from finding it another home. Your question has made me realize what might be the difference for him verses the others. Always thought it was just the variety. None of them have had to be repotted after all these years.
