Hi, Ivy. Even though your zone is much colder than mine, you would literally have to do the same thing I do every year - allow your plumeria to go completely dormant, no soil, no moisture, no light for 4-6 mo. I just put mine in large, black contractor bags and stick the bags in the corners of closets. You could put the bag(s) anywhere that does not freeze. In the spring, the dormant plants are rooted, or if already rooted they are potted or put back in the landscape, and they begin their new growth cycle.
