How many bands of light are best for LED indoor grow lights? There are grow lights that are 5-band, 7-band, 8-band, 10-band, 12-band, 15-band, etc...Which one is the best for indoor medical growing? The quick answer is 6-8 bands of wavelengths. Anything more than six and you are missing essential wavelengths necessary for efficient photosynthesis. Anything more than 8 and you will have unnecessary wavelengths resulting in less efficient growth and lower yields.
When looking at a photosynthetic action radiation chart (from which PAR values are derived) one can see that there are primary peaks at 630nm (red) and 480nm (blue) and a secondary peak at 580nm (orange). To get these three peak colors and cover the area around them it is necessary to have at least 6 wavelengths. Add a couple more crucial wavelengths to balance the spectrum and you have the perfect wavelength ratio that goes into the most efficient indoor growing light. Add too many wavelengths and you now have a less efficient light. More is not better when it comes to indoor growing. Leave the bigger is better philosophy to clever marketers and not to indoor growers.
"Isn't a 12 band system better than a 8-band system?" The answer is a definite "No". If our goal was to just maximize the number of wavelengths we would just get a grow light with all white LEDs. White light has all the colors of the visible spectrum, but then that would defeat the whole purpose of growing with LEDs, where we can zoom in a target the exact wavelengths we need, without adding extra waste. The ability to target the exact spectra needed and cut out the waste is what allows LED grow lights to photosynthesize efficiently. The best LED grow lights will have between 6 to 8 bands and will produce robust, healthy plants that give top yield.