Metal Halide (MH)

Last Updated: August 13, 2018

Definition - What does Metal Halide (MH) mean?

Metal halide (MH) lights produce a high-intensity discharge. Therefore, they are classified as a high-intensity discharge light (HID), in addition to high-pressure sodium lights.

Most of the light within an MH bulb comes from an electric arc that is encased within a small discharge tube. MH lights use mercury vapor to create an exceptionally bright light. Halide salts add a bit of color to the light.

Metal halide lights are efficient grow light choices that produce good light. They are generally considered a better option for cannabis plant growth than fluorescent tubes.

MaximumYield explains Metal Halide (MH)

Metal halides used to grow marijuana plants are usually screwed into a reflector or hood to create even more light for the plants. The main drawback to using metal halides to grow cannabis is the fact that they get very hot. They must be positioned away from the plant’s foliage so it does not inadvertently burn.

MH lights also increase the heat in the grow room or greenhouse so some form of exhaust system must be used to cool down the room and vent out the heat.

MH lights are beneficial during the vegetative growth stage of the cannabis plant because they produce a soft blue light that the plants adore. The lights can be used throughout the plant’s lifespan, all the way to harvest time.

Aside from MH lights, growers also can choose from HPS, LED, plasma, induction, fluorescent, double-ended, and ceramic metal halide lights. Their choice often comes down to what they can afford, and what they can fit in their grow room.

This definition was written in the context of Cannabis
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