What’s the verdict on cheap, department store 300-watt halogen lamps for use in indoor marijuana growing?
Halogen lamps aren’t that efficient as light producers. Even though high pressure sodium (HPS) lamps emit about 60% of their energy input as light and metal halides (MH) slightly less, halogens produce only around 15%. When thinking about the cost of electricity, halogens become much more expensive than HPS lamps.
Halogens produce high amounts of red light and a small amount of blue light. Your marijuana plants will stretch slightly, but they will grow and flower fast. But, for only a slightly higher initial cost, you could upgrade to fluorescents and produce considerably more useable light per watt.