I have been able to bloom over 90% of my Hoyas using T-5 fluorescent grow lights. These lights were not nearly strong enough (at least with a 4 tube fixture) to allow this plant to develop buds. It would grow peduncles, but they would be unable to set buds. I tried growing hypolasia outdoors this summer, but our property is too heavily shaded for the plant to flower. I finally resorted to using a powerful LED light in my basement grow tent, which not only allowed it to flower, but to produce prodigious growth. When I say the LED is powerful, I mean it is extremely bright; so much so that I had to buy special glasses to be able to tend the plants underneath it.