The metal halide lighting is known to emit the most light, and along with that they also emit a lot of heat. This means the grower using these lights for their ganja crop will need to have fans that will keep the growing room the correct temperature. These lights put out mostly a blue spectrum light that is used by the plant during the vegetative growth; yet metal halide lighting can also be used during flowering. The lights can be found in bulbs from 40 to 1,000 watts and one 1,000 watt bulb will produce the amount of light needed for four plants.