Best CMH Grow Light for Your Plants(Updated 2021)

Introduction

The only disadvantage indoor weed growers have over outdoor growers is the lack of natural light from the sun. However, this disadvantage does not deter indoor growers from getting the best out of their cannabis. Indoor weed looks healthier and it grows faster than that grown outdoors.

What you may consider a disadvantage is therefore an advantage. Indoor growers can control the growth of the crops by using nutrients, water and an effective lighting system. Grow lights are therefore a necessity for every indoor weed grower. There are different types of indoor grow lights that weed growers use for the different cycles of crop growth.

The most popular are LED grow lights, MH, COB and HPS grow lights that we have reviewed in some of our earlier articles. There is another kind of grow light, which is also as popular as LED, and HPS grow lights. These are CMH or Ceramic Metal Halide Grow Light.

What Is A Ceramic MH Grow Light?

First, let’s clear up a point of confusion. I’m sure you’ve seen (even just in this article), several different terms and abbreviations.

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 (more on this below in the sections comparing CMH to MH and HPS).

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.

If you’re just interested in the best CMH grow lights, here are the top choices:

ECO Farm CMH 315W Grow Light Fixture Reflector Enclosed Kit

Features:

ECO Farm CMH grow light has the sturdy reflective cap which is made of imported German aluminum reflector with a reflectivity of 98%; contour design and texture eliminate hot spots and dead zones.
Being able to operate more efficiently at higher temperatures means improved performance, greater harvest, and lower cost. Optimize the flowering stage, enhance the red color, and it will produce commodities in vegetables and flowers.
Provides a spectrum closer to natural sunlight than a typical high intensity discharge (HID) system. The higher the temperature, the closer the light is to the sun.

LUMATEK Aurora 315W CMH Grow Light (All-In-One)

Features:

This CMH grow light uses Lumatek digital control panel (sold separately) for remote control and is dimmable. The ballast adopts full circuit protection, including open circuit/short circuit, overheating, over/low voltage, end of lamp life/rectification and EMI suppression.

Full spectrum low calories, closer to the sun, producing healthier plant growth and greater yield. It is a great choice for plants and flowering stage.

PCA ceramic arc tube allows the lamp to work at a higher internal temperature, thereby improving color rendering, output and efficiency.

VIVOSUN 315W CMH Grow Light Fixture

Features:

This CMH grow light is made of Italian VEGA aluminum; compared with traditional lighting settings, this CMH lamp runs significantly cooler and more energy-efficient.

High-tech ballast: The cutting-edge adjustable ballast adopts advanced low-frequency square wave technology, which is efficient, reliable and without electromagnetic interference.

Growth light coverage: VIVOsun recommends using this device to cover about 8 square feet during plant growth, and about 6 square feet during the blooming stage.

This lamp includes a full-spectrum VIVOSUN CMH/CDM 315W lamp, which is an excellent single-light choice for plants and flowering stages.

The Advantages of CMH Grow Lights

There’s a reason people are looking into CMH grow lights, and it’s the huge list of advantages when compared to almost every other grow light option.

Balanced spectrum

Not only do you get a more balanced spectrum that hits almost every sweet spot for your plants but they’re also better at turning your electricity into usable light.

By comparison, HPS and MH lights waste a lot of energy producing light at ranges that are not efficiently used by plants. This means that CMH are more PAR efficient than either HPS or MH, making them a better single light solution.

Color Rendering Index

They also have a more natural CRI (Color Rendering Index). CRI describes how the color of a light source changes how an object appears to the human eyes and how well subtle variations in color shades are revealed. The higher the CRI, the more realistic things look. CMH grow lights are generally rated between 80 to 96 CRI, by comparison, the sun is rated at 100 CRI. This means that CMH grow lights will let you see the true color of your plants without making your grow room look yellow, blue or purple.

Ultraviolet Radiation

CMH grow lights provide UV (ultra violet) radiation, which although being outside of our range of vision is beneficial (at certain ranges and intensities) to plant growth and development. They produce UV-A, UV-B and UV-C Light, but UV-C is generally very harmful to human eyes. So most high quality manufacturers use a glass filter to block the UV-C output while leaving UV-A and UV-B output intact.

Note: All HID bulbs emit some amount of UV radiation. The amount may vary and they’re sometimes shielded. But remember not to look at or work around a bulb with a broken outer glass jacket because UV radiation burns, and this damage is cumulative.

Longer Lasting

Ceramic arc tubes are more resistant to breakdown, so they last a lot longer than MH and HPS bulbs. In fact, CMH grow lights tend to last over 24,000 hours while keeping at least 80% of their original intensity at the 20,000-hour mark. This overshadows the common 10,000-hour replacement rule for HPS & MH bulbs.

Things to Consider When Buying a CMH Grow Lights

Aside from wattage, there’s a lot to consider for choosing the right CMH grow light system for your room, tent, basement, or closet. These are the most important things to think about:

Ballast Support

Because of the unique design of CMH lights, they can only be used with a certain type of ballast. You’ve got to use a magnetic ballast, so think about this before buying – especially if you’ve got a pile of electronic ballasts on hand. 

Heat Output

Just like any high-intensity bulb, CMH lights give off a lot of heat. If you have low ceilings or poor grow room ventilation, you might want to look elsewhere (like LEDs). 

CMH heat output isn’t as high as the heat that’s emitted from HPS bulbs, but it’s still something to avoid for small closets and tents. Just remember that ventilation is key in order to move the hot air out of the room and keep the grow room environment from overheating. 

Color Spectrum

Even though CMH lights have a better-balanced light spectrum than most bulb types, HPS is more capable of delivering high yields during flower. This is why some growers start with CMH and then transition over to HPS during the flowering phase. 

Cost

CMH grow lights are becoming more affordable as the demand for them grows, but they’re still not the cheapest type of light on the market. The upfront cost is a bit on the pricey side, but they cover more area and save more energy in the long run. 

Conclusion

Not only do the CMH grow lights save you energy and produce less heat per watt used and provide very good light spread, but they’re also a complete-cycle growing solution suitable for most green and flowering crops with their balanced spectrum output, UV supplementation and the capability to be hanged in any position over the canopy.

The only downside right now is their high price, which hopefully will decrease as they flood the market and become a more accessible option for growers looking to step up their grow.

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