Part of the reason lighting wavelength is confounding is that various wavelengths are used in growth and maturation signalling while not necessarily used for growth (energy) itself. For example, green light can trigger herbaceous plants to stretch but has the opposite effect on woody plants because the context of the signal is different. Green means a grass or forb is being overgrown and it needs to stretch to get its share of photosynthetic light while it can. But a forest is very different. If you see a two inch diameter tree in the understory, it is likely to be about the same age as a two foot diameter tree nearby. If it is an overstory species, it will bide its time, and even receive some sugar from its more successful neighbors, especially its mother tree via mycorrhizae until the overstory opens up by storm or wind damage, So green means STOP for most trees and blue means GO. Phytochromes sense red and infrared light to build a chemical (forget the specifics) that accumulates during daylight and decreases at night until it reaches a critical level to trigger flowering. Cryptochromes sense the blue/UV end of the spectrum to coordinate the circadian rhythm and sense day length, also triggering flowering. Both are certainly interpreted variously by other genes to determine the flowering date. As far as I know, nobody makes a broad spectrum LED; the white ones act like a fluorescent tube, emitting UV which causes various phosphors to fluoresce in different wavelengths to simulate daylight. Not a big deal for most purposes, but I have yet to find a good bug repellent LED for my porchlight. Insects love UV. _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net>