Hills it is hard to tell because I have only recently started using the LED lights. You can put the lights much closer without fear of heat stress but I am not sure the optimum distance to place from plants. I would imagine that one foot is about as far as you would want to go above the plants if this is the only source of light but in my case I have the panel suspended above trellised plants that are 4 or 5 feet from a southern window. The coloured light given off takes some getting used to but I only have the lights on during the day if it's not sunny. With LED's it's all about the wattage, how much energy is used translates into how much light is given off. There are some very intense spot lights available but they are rather expensive and not what I need in any case. Currently the shelves I use for my Hoyas are about 5 feet long and plan on adding two panels per shelf but because it is sunny this time of year I have only put up one panel to boost the light farthest form the window. I purchased some white light panels to use as well but the red and blue are much better for plant growth and flowering. Mike

I have several Hoyas. A coupl new starts I purchased a month ago and a larger plant I have had several years that I started from rooted cuttings off my sisters plant. I live in noth Indiana so I have to be very careful about putting them outside. My older plant has grown slowly and I repotted it recently because it was on a very small pot. We got a cat which would not stay out of the window I was using and was stressing me and my plants out! Since I only have the one window I can use and the cat adopted it I decided to try LED grow lights which offer red blue yellow and full spectrum light along with a timer a dimmer and a choice of what spectrum you want. All the hoya which include a rope hoya, a tri color krimson queen and the regular one that I had which is hoya carnosa with the white and pink center star flowers have all started growing sensing out vines and leaves. I noticed the leaves are growing bigger and faster so it must work ok!😁 I recently repotted a verigated strand of pearls and added it to my little light party. I’m hoping it does well also!

Bouldergrower is in Boulder, CO, zone 4-5. Tropic, where are you? You guys might be speaking totally different languages. What's sunny in zone 5 may be exact same level of light as deep shade closer to the equator. (Although Boulder's 5,500 feet elevation should also be considered.) This is why all this "full sun / no direct sun / shade" advice read online is of somewhat limited use. I think generally, Hoyas bloom better with intense light, intense enough to bleach the leaves but not to burn them. BUT: leaves often look way better with less intense light, as I think your pubicalyx does, bouldergrower. So, what are your preferences then? You may get away with having the best of both, as the sunny side works well for the blooms, and the shady side creates nice looking leaves. I would consider not changing anything.

I use retrofitted t8 LED fixtures in the cold seasons.I have 4 of them, 4 lights per fixture. They are 6500K daylight. They are on a timer set for 14 hours in the late spring and fall (mid spring through early fall, mine are outside) and 12 hours in winter. As long as the hoya vines don't touch the lights, they are happy in these conditions. That being said, some of mine need more drastic differences in heat/lighting in the winter, to bloom. They get normal household conditions in a West window in the winter.