We usually mention that there are 3 main light colors on our grow light or light spectrum. What we actually talked about it’s the wavelength, the wavelength of a light source that makes it appear blue, or red, or green. The visible light spectrum spans from violet/blue light which have short wavelengths (ranging from 400-500 nanometers) to red light, which has the longest visible wavelength of around 700 nanometers. Because of its short, high frequency wavelength, blue light carries a lot of energy relative to other colors. In fact, if its wavelength was any shorter, it’d fall outside the visible light spectrum into the territory of powerful ultraviolet light.

How Blue Light Effects Cannabis

Blue light is crucial to cannabis. Cannabis plants experience a shade-avoidance syndrome that causes them to stretch if there lower blue light. That’s because, to the plants, a lack of blue light signals that they’re in the shade of other, taller foliage. It’ll compete for exposure by growing longer shoots and eventually exhibit leaf hyponasty (an upward curl of the leaf surface) when cannabis not get enough blue light. Without any blue light, plants get unruly, tall, and poorly adapted for flowering. Because they’re busy stretching for light, they fail to develop the root system that’ll support their nutrition when it’s time to bloom.

Blue light also regulates the opening and closing of stomata. Stomata are the tiny pores that allow gas exchange and CO2 intake. This gas exchange is critical for bringing in the CO2 needed for photosynthesis, and also for cooling the leaves through the release of moisture.