Diffuser placed over LED clusters.
It’s true that an LED grow light doesn’t emit heat so you wouldn’t burn your plants if you placed an array directly on top of the plant canopy. There are other reasons for the minimum mounting height. Based on what Science tells us about how plants use light, we know that they require multiple wavelengths (colors of light) to grow properly. LED designers are able to closely match the absorption peaks for photosynthesis and incorporate these wavelengths into LED grow lighting. When dealing with multiple wavelengths, the light will need space between the LEDs and the plant canopy for the colors to blend.
Applications that do not have the minimum 12-18″ required for proper blending of the colors have the option of using a diffuser. The diffuser basically blends the light as it exits the LED clusters; allowing you to place the LEDs as close as you want. When using a diffuser it’s important to keep in mind that this changes the light distribution and intensity. The LGM550 LED grow light is designed to emit light in a cone shape with the cone spread being about 45 degrees. When fitted with a diffuser, there is little light loss from the diffuser itself but the cone spread is now approximately 180 degrees. We have roughly the same amount of light but a decreased intensity as the light is spread over a larger area.
