What is the effect of black light on plants?

Ultraviolet is invisible to the naked eye, it comes just before the visible spectrum. Most of UV light is absorbed by the atmosphere before light reaches the surface of the earth.

Black lights emit UV radiation in the UVA and UVB region. Chlorophyll found in plants strongly absorbs long wavelengths in the UVA region.

Excessive UV radiation can have a negative impact on phytopigments. Researchers have found that plant growth can be improved by removing UV light from white light sources.

As we’ve seen in another article, UV light, especially UVC can kill certain pathogens. But an excess of UV light can also destroy beneficial microbes which play a role in the growth of plants and other organisms. Nature is a subtle balance. The strongest form of UV light can also damage DNA.

Plants, like all organisms, tend to adapt themselves to a changing environment. Studies have shown that crops exposed to more UV light started producing molecules to counter it. Which means that, after a few mutations, they would be able to cope with a natural excess of UV light.

Can plants benefit from UV light?

There is a plant in particular which benefits from UV engineering: Marijuana. Ultraviolet light increases the production of THC and CBD, as a coping mechanism to protect the plant from harmful UV radiation. THC and CBD are the active ingredients of the plant, that’s why UV light is usually added to LED grow lights used by marijuana producers.

LED Grow Light with uv light
LED grow light

Plants do NOT need UV light but in certain circumstances their reaction to UV light can enhance their properties.

Moreover it’s worth noting that plants will NOT grow if only exposed to black light. They need a much wider light spectrum to ensure their healthy growth. Growing plants under black light would be like growing them in constant winter conditions, which would hinder their development.