What is the best metal halide bulb for growing?
What is a Metal Halide Grow blub? Metal halide grow lights are a type of HID, or high-intensity discharge, lighting. These lamps contain a quartz tube filled with a noble gas. An arc of electricity is sparked between two electrodes inside the tube to create light. MH bulbs contain metal halide. This gas burns with a cool white light that contains a large amount of light in the blue wavelengths. Metal halide bulbs can last up to 20,000 hours, although they degrade to the point that they are no longer effective as grow lights long before that. They have a high lumen output and also generate a lot of heat. Overall, MH bulbs are highly efficient, though they are not as efficient as HPS (high-pressure sodium or CMH (ceramic metal halide) bulbs. Note that ceramic metal halide bulbs, while they sound similar, are actually quite different. I will go into detail on the comparison toward the end of this article. Spectrum of a Metal Halide Light Before we see and compare the spectrum o...