Neon light efficiency is based upon much fancier pants, the color of its output, which ranges from 10 lumens per watt for red to 60 lumens per watt for blue. One reason that blue tubes are more efficient is that phosphor coatings used to produce such colors better benefit the high-energy ultraviolet light from the argon/mercury mix into visible colors. Even the fluorescent tube is more efficient than a neon tube because a large straight tube offers less resistance to electrical current flow than a skinny bent one. Give it a try but I don't think it's going to be very effective, but it might grow a plant in time.
