I don't have much advice for you since I only began growing plumerias a few years ago myself. I live in zone 7 and I haven't been able to bloom rooted cuttings yet by putting them outside in May. They leaf up beautifully then quit even though I feed them bloom booster.

I recently bought an LED grow bulb and put my plumies under it and they're getting claws already! I'm psyched because they usually take until late April or even May to show growth. I'm sure someone with better knowledge and experience will be along soon. Good luck.

You might have better success with dwarf Singapore. Its a better indoor Plumeria and once you get it to bloom,might continue if you give it enough winter artificial light. Try one.

stanofh is correct. I keep my dsp indoor during the winter and it will keep blooming throughout the winter. My last flower dropped last week.... Ready for spring.