What Is A CMH Grow Light?

Ceramic Metal Halide (CMH), Light Emitting Ceramic (LEC) and Ceramic Discharge Metal Halide (CDM) all refer to the same thing. CMH is the most common term. Another point of confusion concerns their relationship to metal halide lights.

CMH grow lights are a variation of MH, but they are quite different. Instead of using a quartz tube, they use a ceramic one (more here), similar to an HPS bulb.

This allows a higher arc tube temperature, which in turn allows a better mix of gases to produce a more optimal spectrum.

The light produced by a CMH bulb is much closer to natural sunlight than either metal halide or high pressure sodium (with a CRI of 96). It is, for practical purposes, a perfect combination of MH and HPS in a single bulb.

Advantages Of CMH Light

  • Spectrum

The CMH light spectrum combines the red-heavy HPS spectrum with the blue-heavy MH spectrum in one bulb, making it the perfect light for all stages of growth.

With a high CRI, it is extremely close to natural sunlight, which is great for your plants and for your eyes (plants look more natural, making it easier to spot any discolorations or other issues).

  • Efficiency

Ceramic metal halide gives you a much higher PAR (the amount of light that is usable by plants) per watt than any other type of lighting, apart from the most expensive LED fixtures.

  • UV Light

The CMH light spectrum also contains UV light of all type. Since UV-C light is harmful, the lamps use a glass filter to block that range.

This leaves only UV-A and UV-B light, which many feel is beneficial to yield quality. There is no need for supplemental UV lights when using CMH grow lights for indoor growing.

  • Lower Heat

CMH grow lights run much cooler than their MH and HPS counterparts. This reduces (or eliminates) the need for additional cooling equipment. They run hotter than light emitting diode lights, though.

  • Long Lifespan

CMH bulbs last much longer than other HID or fluorescent lights. The standard rule of thumb for HPS or MH bulbs is to replace them after 10,000 hours of use. Good ceramic MH bulbs last over 20,000 hours. Moreover, they still retain 80% or more of their initial light output after 20,000 hours. HPS and MH lamps deteriorate much more quickly.

Best Ceramic Metal Halide Grow Lights: Reviews

Below are the best ceramic metal halide grow light kits and the best ceramic metal halide (cmh) grow lamps currently on the market.

ECO Farm Single Ended CMH 315W/350W Grow Light Kit For Indoor Plants

  • This is an idea greenhouse supplemental lighting fixture with advantages on deep light penetration and uniform light distribution.
  • Equipped with high performance low frequency square wave electronic ballast ensures the stable light output as well as extend lamp lifetime.
  • Optimal light output by incorporate with a 99% reflectivity glass optical silver-coated reflector.
  • Controllable output. With the output dial, you can select an output power, adjusting your light to changing circumstances or growth phases. RJ ports allow you to connect external controller for control multiple light fixtures.

ECO Farm CMH 315W*2 Bulbs Grow Light Kit Reflector Ballast Suitable For MH/HPS Lamp

  • Stepless adjustable function, it is easy to switching these models, beam angle and light spread area for different usage. Create a more focused coverage area and ideal for a condensed grow space to help plants grow quickly.
  • High-Reflectivity Aluminum Hood: The cutting-edge hood made of aluminum boosts reflectivity by 20% compared to standard aluminum reflectors; Unit has an excellent light reflectivity rating of 95% ; Contouring of the polished reflective surface ensures no hot spots or dead spots
  • Hammered surface design enhance the diffuse reflectance and ensures uniform light output
  • Solid braided rope & reinforced metal internal gears to ensure top-safety; Assembly is required, easy to set up.
  • The reflector's design offers multiple points of reflection for optimum light coverage and canopy penetration

ECO Farm 315W CMH Single Ended Grow Light Kit 95% Reflectivity Grow Light

  • ECO Farm 315W CMH kits run significantly cooler compared to conventional lighting setups and do not need to be cooled with ducting and fan; extra efficient with energy not lost to heat.
  • Electronic Ballast 120-240V with advanced low-frequency technology, designed specifically for CMH 315W grow light, high efficiency, reliability, and no electromagnetic interference
  • 315W CMH grows light bulb (3100K) provides the full light spectrum and can be used for bloom stages better.
  • Unique open rated lamp construction reduces radiant heat from the arc tube
  • A higher temperature creating light much closer to the sun’s.
  • The 315W light bulb is optimized for the bloom phase which is full-spectrum, it will produce the goods in both vegetable and flower expect to see increased growth rates, tighter internodes, an improvement in overall vigor and an increase in final weight.


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