the two posts are right, halogen is for lighting up large dark areas, not growing, it is not the right wavelength, 1 Metal Halid (MH) or High Presure Sodium (HPS) is good, also, Compact Floros (CF) work, but you would need around 16! So going with a MH or HPS would probably be the cheapest way, and a 1 400 watt or more bulb would cut it just fine/