Billy,
Since African Violets are rosette plants and face up, so to speak,
they lend themselves to being grown under fluorescent lights very
well. Unfortunately, due to hoyas vining nature, it's a little more
difficult to grow hoyas under lights, especially after the plants
start to get larger.
I start all of my cuttings under fluorescent lights and the cuttings
do very, very well, so, yes, hoyas can be grown very well under just
fluorescent light. Because the foot candles from fluorescent lights
drop off very rapidly, just a short distance away from the tubes, when
plants start to get large, only the top part of the plant near the
tubes is getting a lot of light and the bottom part of the plant
suffers.
Hydroponic folks put a reflective film (Mylar?) on the walls of their
growing rooms and using high pressure sodium or metal halide (or both)
lights and fixtures and you could probably grow hoyas just fine since
the light from these bulbs is so intense. You'd actually need to
watch that the vines didn't get too close to the bulbs and get burned/
scortched.
Sodium light is very high in the red end of the spectrum and is good
for getting plants to bloom and halide light has more light in the
blue end of the spectrum so is good for keeping plants compact. When I
grew orchids under my sodium light, I used a Sun-Agro 430w bulb
because it had 30% more blue spectrum than a normal sodium light and I
didn't need two fixtures and two types of bulbs.
I have a high pressure sodium light on a 9' track with a light mover,
in my basement, and I used to grow orchids under this light setup. Due
to the intensity of the light, it was as if I had a greenhouse in my
basement. I have gotten rid of almost all of the orchids and just have
a couple in my windows now. My basement is unfinished and is quite
cold during the winter (high temps of about 60°F) so it's too cold to
grown hoyas under the light down there. I may need to see if I can put
up a wood frame covered in plastic around the area of the light to
hold the heat from the sodium light and that may make it possible to
grow some of the cool to intermediate hoyas under the light in my
basement.
If you try any type of light/fixture/etc. for your hoyas, be sure to
report back and let us know your experiences.
Thanks,
Mike