Do LED lights emit UV?
White LED lights do not emit UV rays. White LEDs emit wavelengths in the visible range in blue, green and red. White LEDs also emit some far red which is just in the visible range and can be seen as dim red.
Specialist UVA LEDs are affordable and effective in emitting UVA photons. However, UVB LEDs are very expensive and not very efficient. Fluorescent UV grow lights are much more effective at delivering UVA and UVB for plants
White LEDs are safe for people and plants
These wavelengths of light are safe for humans and will not cause any damage to eyes or skin. Very bright light can damage your eyes but the risk from a standard home LED light bulb is minimal. Similarly white LED grow lights will not cause UV damage to plants.
White LED light spectrum chart
UV LEDs emit UV rays
Why use UV LEDs for humans and plants?
UVA LEDs are affordable and effective in emitting UVA photons. UVA rays cause tanning and the shorter wavelengths of UVA also cause sunburn. UVA radiation is proven to contribute to the development of skin cancer.
For plants UVA in longer wavelengths from about 370nm to 400nm can cause photosynthesis but at low efficiency. UVA can help keep plants short but so can blue light. UVA can improve plant health by strengthening the cuticles where the plant branches join the main stem but no other positive effects are proven.
UVB LEDs are very expensive and not efficient. UVB penetrates and damages the outermost layers of your skin. Overexposure causes suntan, sunburn and, in severe cases, blistering.
UVB can effect plants by stimulating the 'sunscreen response'. With UVB exposure plants can increase production of resins and oils in the form of secondary metabolites. In particular UVB can enhance the production of terpenes and flavonoids in plants. This means your flower will smell and taste better.
UVC LEDs are available but damage cells and can cause cancer. UVC should never be used around people or plants.
Fluorescent UV lights emit UVA and UVB more effectively than LEDs
Although UV LED technology has improved Fluorescent fixtures are much more efficient and much less expensive than UVA and UVB LEDs.
See our comparison test of LED and Fluorescent UV grow lights here
