myth #6. LEDs are ("ultra-bright", "extremely low power", "used by NASA", "monochromatic", or pick your own catchphrase) therefore they are the best grow lamps.
LEDs look ultra-bright because they are small and emit all the light in one direction. This is great if you want to grow a single blade of grass and not much help for most anything else. LEDs are extremely low power because they are small and emit very little total light. This means you need a lot of them to grow anything useful and then they use a lot of power. NASA has experimented with LEDs because they are small, light, and nearly indestructable. None of these features are particularly valuable to the average plant grower. Many LEDs emit a very narrow range of light wavelengths, which means they can be calibrated to emit only the light most useful for plants. That's exactly what a GRO-LUX lamp does and the fluorescent GRO-LUX does it about five times more efficiently