One of the most difficult decisions for any ACMPR grower is deciding on the type of lights to use for an indoor grow op. LED, HPS, CMH, CFL… all of these letter combos can start to get confusing fast. 

We’re not going to sit here and tell you that CMH grow lights are the best in every way, but growing with CMH bulbs does come with some benefits. 

CMH, short for ceramic metal halide, emits highly intense lights, similar to HPS grow lights. But unlike HPS, CMH offers the full-color spectrum and mimics sunlight so that your plants don’t miss out on anything. 

Sure, there are a few downsides to using CMH bulbs, but this is the case for every type of bulb. It’s up to you to weigh the pros and cons to decide whether or not CMH grow lights – like the ones we’ll cover here – are right for you and your plants. 

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How to Choose Your CMH Grow Lights

Choosing CMH grow lights is like choosing any other type of light; the first step is to consider your grow space and how much light coverage you need. 

The light coverage of every CMH grow light is determined by its wattage – a 630W CMH grow light offers almost twice the coverage of a 315W CMH grow light. The popular 630W CMH lights can cover a veg area of 5’ x 5’ and 4’ x 4’ in flower. 

So first thing’s first, decide on your wattage, then you can focus on other important factors like light efficiency, design, and cost. 

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. 


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. 

Best Overall CMH Grow Light Kit

If you’re looking for a complete CMH grow light kit, the key is to not only focus on the bulb quality but the entire unit as a whole. Consider what’s included – like rope hangers, a magnetic ballast, a reflective hood – before buying, and of course, you’ll have to decide between 315W and 630W. 

BloomGrow 630W CMH  



If 630W is right for you, there’s no CMH grow light kit that compares to the BloomGrow. When your plants are flowering, this light can cover up to 16 square feet of space, and even more in veg. The initial price is high, but the high coverage area means bigger harvest and less cost. 

BloomGrow is compatible with both 120 and 240V and it can easily replace any 1000W HPS system. While standard MH bulbs have an average lifespan of 10,000 hours, you’ll likely be using the BloomGrow for at least 24,000 hours of growing. 

Best 315W CMH Grow Lights for a Small Grow

630W CMH lights aren’t for everyone, especially if you’re short on ceiling space and have to hang your lights closer to the canopy. Whether this is the case or you have another reason for choosing 315W CMH lights, we’ll always recommend the Vivosun. 

Vivosun 315W CMH 


Best For a Small Grow
Best For a Small Grow


The hood design of the Vivosun 315W CMH is different from any other grow light we’ve come across. It features mirror panels connected with textured corners, which helps to deliver more even coverage and eliminate hotspots and dead zones. 

It comes with a cutting edge ballast that features advanced low-frequency Square-Wave technology for high efficiency, reliability, and no electromagnetic interference. Another cool design feature is that the ballast is built-in to the inside surface of the light, keeping everything nice and streamlined. 

It has a coverage area of 9 square feet in veg and 6 in bloom and it was designed to run cool while saving energy. If you’re tired of the inefficiency of your old HPS system, this is an amazing upgrade. 

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Best CMH Grow Lights for Indoor Growing

For indoor growing, you’ll want to choose a CMH that is easy to handle – in other words, it shouldn’t be impossible to make quick adjustments to keep your plants happy. This is just one of the great features of the Vivosun 315W Suspension System. 

Vivosun 315W Grow Light and Suspension System  



With this light system, even small-time growers are able to get professional results. This Vivosun runs significantly cooler than other high-intensity light systems, so you won’t need to install an intense ventilation system to prevent overheating. 

The hood design has 98% reflectivity and its contour and texturing completely eliminate hotspots and dead zones. The coverage is the same as the last Vivosun, but many growers prefer this one for it’s easy to use setup and more accessible ballast. 

Best 630W CMH Grow Lights

The BloomGrow is just one of the many high-quality 630 CMH grow lights available to growers in Canada. If you’re looking for something that’s slightly more budget-friendly, you’ve got some options, like the SunStream Double Bulb system. 

SunStream 630W Double Bulb 



In addition to Vivosun, SunStream is one of our top picks for grow light manufacturers, mainly because they deliver high-quality products and place a huge focus on customer service. Not to mention, grow rooms that use the SunStream 630W light tend to have high yields. 

The SunStream 630W emits full-spectrum light and comes with a high-tech ballast, highly-reflective hood, and two 3100K CMH bulbs. To clear up any confusion, this is a single-ended fixture that comes with two bulbs included (it’s not a double-ended system).

Best LEC 315W Grow Light (Professionals)

Just like Vivosun and SunStream, Sun System is another grow light manufacturer we can trust. Professional-level growers often turn to Sun System products because they’re powerful, reliable, durable, and effective for delivering high yields. 

Sun System Grow Lights – LEC 315W 



Because of its high price tag, the LEC 315W by Sun System isn’t for the cannabis growing hobbyist who’s growing 3 or 4 plants in a closet. It’s specifically designed for professional-level indoor grow ops (or ACMPR growers with high plant counts). 

This light system was engineered for high efficiency, so if you can get past the high upfront cost you’ll love the energy savings that come along with the LEC 315W. The ballast is rated to last for up to 50,000 hours, so plan on getting lots of use out this CMH grow light. 

Best CMH Light Bulbs

If you’ve already got a ballast and hood setup, there’s no need to buy an entire CMH grow light kit. You’re better off investing in a bulb that’s compatible with your current system, like the Philips Master 3100K. 

Philips Master 3100K  



The thing we love most about the Philips Master bulb is its high photosynthetic photon flux (PPF), which essentially just means that it helps plants to perform photosynthesis more efficiently. It’s a compact and efficient solution for the “horticulture market”, AKA cannabis growers of Canada. Just be aware that this bulb is designed for a low-frequency ballast. 

What are CMH grow lights?

CMH grow lights have many names – like light-emitting ceramic (LEC) and ceramic discharge metal halide (CDM). They’re a variation of the traditional metal halide light type with some features of HPS technology (high-pressure sodium) added into the mix. 

Traditional MH lights use a quartz tube instead of the ceramic arc tube that’s used in CMH bulbs. Ceramic operates at a much higher pressure than quartz, and this allows CMH grow lights to emit a more balanced color spectrum. 

Why should you use CMH lights and what are the advantages?

A balanced color spectrum is just one major advantage of using CMH lights in your grow room. Another big perk is its better PAR efficiency, which essentially just means that it gives off a lot of light. And compared to MH and HPS lights, CMH wastes close to no energy. 

CMH grow lights are extremely long-lasting, partly because they’re resistant to heat and other common bulb issues. High-quality CMH bulbs run for 24,000 hours or more – when you break that down it’s equivalent to about 3 years. 

Lastly, CMH bulbs offer better color stability and provide UV light. So not only do they give off the full spectrum of light, but they also give off more UV light than the average bulb. This is great for veg when the plants need to establish strong branches for the rest of the grow.

What’s the proper CMH grow light distance from the plant canopy?

It depends on the light wattage (remember, more watts gives off more heat). The two most popular sizes are 315W and 630W, so let’s focus on those. At the very least, your plants should be at least 18 inch from a CMH grow light, the keyword here being very least. 

For measuring CMH grow light distance from plants, 630W lights need to be hung even further away. If you’re trying to cover more space with a higher wattage, just be sure to hang your 615s between 24 and 26 inches from the plant canopy. 

This is the general rule of thumb, but it’s not the case for every CMH light on the market. Some require even further distance from plants, even as much as 3 feet away. 

Comparing CMH vs LED vs HPS

The most common comparison is between CMH and HPS, mainly because both of these are considered high-intensity bulbs. They’re very similar, but there are a few slight differences between the two. 

CMH lights give off a more balanced color spectrum, while HPS technology focuses on the red light wavelengths (which is more ideal for producing beefy buds during flower). In terms of efficiency, CMH lights win hands-down, plus they have a longer lifespan on average. 

CMH and LED lights are completely different in the way they operate. LEDs give off very little heat and they’re the best when it comes to efficiency, but they come with a hefty price tag. 

Since they don’t give off nearly as much heat, LEDs are a great choice if you’re low on ceiling space or you’re working with a small grow op. 


We’ve covered some solid CMH grow lights here, so you really can’t go wrong with any one of them. The main deciding factor once you’ve confirmed that CMH lights are right for you is whether you need 315 or 630W. 

If you’re handling a small grow space, our recommendation is the 315W Vivosun, but for more coverage, the BloomGrow system is our top pick. Whichever one you choose, let us know how it goes in the ACMPR Facebook group. 

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