I'm trying to find the right quantity of light myself. while its fairly rough information. I'm getting the feeling of 100+ watts per plant is recommended at flower. However I do know a bit about using lights for growing other stuff(algae) I can tell you that while the plant is small if you place the bulb close to the plant with a reflector on it you should be good until it out larger. The PAR(photoactive radiation) of a light at 6" is many times greater than it is at 12". If your looking for bang for your buck CFLs with a parabolic reflector is best(home depot). the spot CFLs are not all that great.