HI Guys,
Here's how we do it:
we have 2 commercial fixtures w/8 lamps over a 4' x 3' shelf about 10" above the plant tops.
We rotate the bulbs to make sure we get the widest spectrum possible from artificial light.
We're doing this:
cool white, grow lux, cool white, warm white, cool white, grow lux, cool white, warm white
Our experience is, that cool white is the best overall (we use philips) however for fuller growth, the warm and grow lamps seem to give the plants just enough extra spectrum for flowers to bloom and stay healthy for long periods. We have some utrics that have been in bloom for over a month... with the buds just NOW starting to fall off. So I think it's working quite well.
HOWEVER, when moving to this spectrum of light, we did discover that it was too intense for most nepenthes, but perfect for flytraps and sarracenia. The sundews, butterworts and nepenthes are on racks where the lighting is almost 3' above the plants.
As for the sun bulbs. They work well when you don't have them right on top of the plants. In the case tony was talkin' about, I'm not sure of the position or wattage of the bulbs... but we did have a rack with sunbulbs and cool white about 12" from the plant tops and it totally messed up the flytraps. But we also have a 16 hour/day cycle which may have been too much.
We'll still use sunbulbs in some cases... instead of the warm white... so in that rotation above, I would exchange the warm for the sun. We'll probably do this with the taller sarracenia that we have to grow indoors.
Anyway, if people start shoving metal halide or high pressure sodium down yer throats as grow lamps... our experience shows that they're WAY too hot for the foot candles they produce and significantly more expensive to operate. Though they are good as supplemental lighting in a greenhouse where the days need to be extended... just not for primary growth. (of course, that IS my opinion only
)
If you're working with space for just ONE light.. I would suggest cool white.. as it seems to be the best overall... when using by itself.
Hope this helps!