This is an interesting thread for sure. I too have heard that color temperatures are less important than what is commonly believed. The reason there is such an emphasis on the colors is because of the pot community; I heard somewhere (very authoritative, I know! lol) that the switch in colors is only needed to stimulate good THC production in the MJ. :drool: :hmm

I did some primary literature searches and it seems the issue is a lot more complicated, and light intensity and duration also have roles in regulating gene expression. Furthermore, lots of studies are done in arabidopsis, which is a) an annual, and b) a dicot and a world apart from orchids...can those studies really be translated to the plants we grow?

Maybe some plant physiologist can shed some light (ha) on this matter, but from my quick search on pubmed, it seems that there is actually very little conclusive evidence that supports light colors favoring flowering or growth. Until I know for sure, I'll just stick with the 5000k bulbs and resist messing around with plant cycles and circadian rhythms!

I have no clue about colors, but when I grew indoors under HID lighting, I found I could bloom just about anything including terete vandas under a combination of high pressure sodium and metal hallide lights on moving tracks. Day length and humidity are also crucial for some species, etc.

A little dated (I wrote this in 93' for AOS)...
Grow Orchids Under HID Lighting Metal Halide High Pressure Sodium

Ken