Metal Halide (MH) Lights emit light primarily along the blue spectrum, and are the ideal choice for growing plants in the vegetative stage, as well seeds or clones. MH lights are well balanced, and can be used throughout the entire growing process, encouraging short and compact plants. Metal Halide Lights have a long life expectancy, and the decline in lumens (intensity) as the lamp ages is very slow. This light is the best single choice for vegetative growing of a variety of crops.