The powerplant metal halide super veg bulbs are designed for the vegative growth phase of plants during the vegative growth phase plants prefer blue spectrum light which these bulbs emmit the benefit of metal halide lamps is that plants do not stretch as much and instead remain very squat and develop more shoots metal halide bulbs are used with the same equipment as your main sodium flowering light when your plant has reached its flowering stage simply swap over to a hps bulb remember to u