WIKI ANSWERS- Black light is, essentially, another form of UVA light, similar to fluorescent light which isn't so different from natural "white" sunlight. Theoretically it shouldn't affect it too much, but I also know that chlorophyll (the material that makes plants appear green) is at least partially fluorescent, and supposedly it glows red under black light with the right conditions. I've never personally seen a plant grown only with black light, but if anything it would change the color, not the actual ability to grow.