blacklights give UVA radiation aka photons with wavelength above 400nm. peak around 370nm?(ne1 confirm?) plants absorption peaks below 400nm but they still absorb smaller amounts of photons above their peak. with green light however there really is not much absorption which enables gardeners to use green at night to view plants. blacklights and their above 400nm photons do not consist of the visible light spectrum (400-700nm) and so as a result they dont generate light us humans can see so it would still be dark if you turned a blacklight on when its dark. furthermore, from what i understand carotenoid pigments also absorb UVA.
