Hey all
I recently did some research, consulted my botany texts, and found out about 'weins' law.
Check it out:
"there IS a relationship between a colour temperature and the peak wavelength in its spectrum. It's called Wien's law.
Wavelength (nanometers) = 3,000,000 / Col temp (Kelvin).
So at 4,500K, the peak wavelength is 666nm (red) at 6,000K the peak wavelength is 500nm (bluish green) and at 7,500K the peak wavelength is 400nm (deep blue)"
Ok, given 'weins law', and knowing the wavelengths that chlorophyll A and B function at, we can figure out the best color bulb to use
Chlorophyll A: absorption peaks at ~440 nanometers (blue) and ~660 (red)
440 nanometers = 3,000,000 /
6,818K
660 nanometers = 3,000,000 /
4,545K
Chlorophyll B: absortion peaks at ~470 nanometers (blue) and ~640 (red)
470 nanometers = 3,000,000 /
6,382K
640 nanometers = 3,000,000 /
4,687K
Now...I have supplied us with the most useful kelvin values for chlorophyll A and B, but as for what is needed in vegging vs flower I cannot yet attest to. I've always heard blue for veg red for flower, and it seems to work for everyone, so I dont doubt it.
The only place i'm seeing a departure from popular wisdom is the kelvin values for the red, flowering light. 2700 is way off from the red absorption peak, the best value we can look for is ~4,600K (or so these numbers are telling me).
I'm planning on 4 or 5 105watt CFL's @ 6500K for veg, then switch them all to 105watt CFL's @ 4100 (or possibly 5000K, i'm still deciding) for flowering.