What is Full Spectrum Lighting?
Full spectrum lighting generally refers to light delivery across the entire visible spectrum of light. Many would argue that “full spectrum” should mean the entire spectrum delivered by the sun, as can be seen here:
For the purposes of plant growth, the entire range of light provided by the sun is not utilized. Most plants absorb light across the full visible spectrum. Light at 550nm (GREEN) is absorbed less than all other colors (by only about 3%!) – this is why most plants appear green to us. Almost no light is absorbed above 750nm (FAR RED).
Just because light it is absorbed does not mean it is put to use by the plant, making carbohydrates for cell growth. However, as can be seen in the image below, plants utilize the entire visible spectrum to flourish.
The most common frequencies known to indoor growers, and cited extensively by both HID and LED grow light manufacturers, are the Chlorophyll A and B absorption peaks. Sadly, almost universally ignored are the “accessory pigments” such as the light harvesting Beta Carotene, and Phycoerythrin and Phycocyanin protein pigments that process a tremendous amount of light to be utilized by the Chlorophyll processes. This is contrary to many manufacturer’s claims that these middle frequencies, especially green light, are not used by plants at all! Further, LED grow light manufacturers that provide only blue and red light are missing out on a huge portion of the visible spectrum vital to plants.