Indeed, black lights are usually near to or in the UV range, from about λ 350-400nm (peaking at around 370-375). *NOTE* Other common UV lights may emit peak light levels around λ 360-365nm; one such device is a Woods Lamp, frequently used in forensics and medicine. In either case, this is nowhere near the spectrum that plants need to actively photosynthesize. Most plants have an absorbance spectrum similar to the graph illustrated below, which includes reds, yellows, oranges, and blues (but very little green, which is why we see green leaves - green light is the prominent spectrum that is reflected and not absorbed by the plant). As you can see, chlorophyll a does reach into the UV range, however only marginally and on a declining slope. Chlorophyll b does as well, though at even lower levels. A much better investment (in all aspects) would be to go with full spectrum visible light output devices (or sunlight), as these are the spectrums used in photosynthesis. Hope this helps :smokin:.