Kelvin is simply a way to determine how humans perceive the color of the light being emitted from the source point (not reflected off of a surface). In visible spectrums the Inda-Gro phospor emits a 4800K CCT. This number is of little use to plants though. If you look at the XYZ coordinates on the Plankian Locus
http://en.wikipedia.org/wiki/Planckian_locus you can follow the monochromatic values on the edge of the graph and you'll see the values between 380-700nanmeters. Then look at the kelvin curve and exactly where the kelvin values fall within the X,Y coordinates and it's easy to see that these are values that can be achieved dozens of different ways by raising X and lowering Y and vice versa and so on).
The reason I bring this up to this degree is that the value of Kelvin to plant net action absorption spectra is mostly a marketing gimmick to make people buy both a veg and a flower lamp based on different kelvin ratings which are custom 'tailored' to meet plant net action spectra depending on whether it is in a vegetative or flowering phase of growth.
On the other hand there are some LED manufactures who go the other way in narrow band spectra claiming their lights are 100% PAR usable light with 'No Wasted Energy'. Well that is marketing in the other direction since they still emit wavelengths that fall within the 400-700nm PAR regions, they just pick narrow bands and exclude others that are important to overall plant development. In fact if you consider that a plants net action spectra is absorbing, to varying degrees, wavelengths between 400-700nm it means ANY light within 400-700nm is PAR usable. Not such a dramatic statement when you consider it from that perspective.
To illustrate my point take a look at the spectral distribution graph at the bottom of page two and you can see these are two spectrums 440 and 660nm being peaked to the exclusion of other spectrums:
http://www.lumigrow.com/wp-content/themes/agivee/images/docs/LumiGrow-Pro-SpecSheet.pdf Of course if it were that simple anyone with a bin full or 440 and 660 nm diodes it would be game over. To exclude these other spectrums in LED design has already proven to be problematic to healthy plant (Emerson Effect) response when not able to absorb spectrums that would be found in nature. If Lumigrow would like to run a side by side I'm up for that.
You don't really need a physics degree to understand plant lighting. If you do your research and buy what works as shown by other growers to be successful and not get swept up in the hype, both you and your plants will appreciate it.
