green light is important.......like many have said red and blues are inadequate in stimulating the healthiest responses. All the stoners with " real practical experience" probably know better but NASA disagrees
NASA Technical Reports Server (NTRS) - Sole-Source Lighting for Controlled-Environment Agriculture
Green light.
Green light (500-600nm) falls between broad-band blue and red light
along the PAR energy spectrum. Green often is disregarded as an unimportant
waveband in photosynthesis because absorption spectra of extracted leaf chlorophyll
pigments indicate very weak absorption in the green region of the PAR. Because
chlorophyll has major absorption peaks only in the red and blue regions, researchers
initially selected first red, later blue, LEDs for first-generation LED arrays to support
plant growth. However, intact leaves do absorb considerable green light, and in a
relative quantum-efficiency curve for photosynthesis vs. PAR wavelengths, some
wavelengths of broad-band green actually are more efficient than certain
wavelengths of the blue band. Overall, however, broadband green is slightly less efficient than broadband blue. However, when leaf canopies close, red and blue light are absorbed strongly by upper or outer leaf layers, whereas green light penetrates to interior leaf layers, where it subsequently is absorbed and drives photosynthesis of the inner canopy (14). Thus, light sources containing some green can be more effective in stimulating crop growth than are red + blue sources alone,much as when
foliar canopies are closed. When applied together with blue light, green has effects
opposite to blue on stomatal aperture (15). Yet another useful feature of green light
is that the human eye perceives red + green + blue (RGB) light as white light, so if all
three wavebands are present simultaneously in plant-growth light, researchers and
growers are able to visually evaluate the stress status of crops, the incidence of
physiological disorders, and “true” leaf color (the way it looks outdoors), whereas if
only red + blue are present, green tissue looks purple, grey, or black, and
physiological stress or disease diagnosis is difficult(...)
Great info, thanks!