Quote Originally Posted by Al B. Fuct
Unfortunately, plants don't live on just a couple of narrow peaks in the spectrum.
They can. If they couldn't, LED grow lights would not work at all. Just because I don't live on pop-tarts, beef jerky, and vitamin pills, doesn't mean I couldn't.

Yes, cannabis prefers a blue emphasised spectrum for veg and a red-orange spectrum for flowering- but notice I said spectrum, not wavelength.
Yes, chlorophyll can absorb a spectrum of light, but i doubt it can tell the difference between different shades of red. It can tell the difference between blue and red, but that seems to be all. And LED systems are set to use the wavelengths that are most readily absorbed in the blue and red spectrums.

When we say wavelength, we're referring to a pronounced, narrow bump in the spectral curve around a central frequency. 'Spectrum' refers to a broad band of different wavelengths between an upper and a lower limit, with light of relatively equal amplitude (intensity) between the points.

Back to first principles. You can bet that the plant has evolved to grow in sunlight. Whatever lighting system you cook up, the closer it is to Old Sol, the more likely cannabis will like to grow under it. The sun is a broadbanded light (and other EM radiation) source. Current tech LEDs are not.
This last part I take issue with. Does any indoor grower try to emulate the sun with their lighting system? No, they try and emulate the chlorophyll absorbsion spectrum. Plants, and all other living things, have evolved to survive in the natural environment, but that doesn't mean that environment is ideal for them. I for one, prefer my house to the african savannah.

I attached a nice graph of an LED grow light spectrum superimposed on the chlorophyll absorbsion spectrum.
khronik Reviewed by khronik on . LED grow lights... input please. Hello guys, I'm exchanging eMails with a representative from a LED company. I asked him if they could produce a custom light for growing, and here's what he told me: Our options are as follow: 940nm, 850nm, 660nm, 630nm, 610nm, 590nm 570nm, 530nm, 510nm, 470nm, 460nm, 400nm and a total of 64 LEDs in the bulb. Rating: 5