I've been reading up on all types of lighting lately and came across plasma lighting. I know it's expensive and such, but does it grow better weed? Better than LED or HID? I haven't ever came across weed that was grown by a plasma light.
http://forum.grasscity.com/lighting/454702-sulphur-plasma-grow-light-systems-mps.html?hl=plasma+grow this thread has some info on it you might be interested in
by far the best spectrum in terms of even distribution of radiation, or 'likeness' to the sun's output, but yea, expensive. ive never seen them used but judging by the spectral distributions of the ones sold as grow lights, they should rock pretty hard. Its difficult to beat a properly designed led though because they emit light only in bands the plants can use, so much less PAR radiation is lost in the dead zone centered around 4000k.