PAR

Most gardeners know lumens to be the “measure of the total ‘amount’ of visible light emitted by a source.” What they often do not know is that this “visible light” only refers to light that is visible to the human eye with no regard to the distribution of that light energy over the spectrum. Why does this matter? Imagine three lamps: let these lamps be red, blue, and green, and let each emit the same number of watts of optical energy. On a lumen scale, the red and blue lamps would have a much … [Read more...] about Plant Lighting Pt 1: Plants see PAR, humans see Lumens