CMH vs. LED
Which Grow Light is Best for You?
Grow lights have evolved from heavy magnetic, in-efficient ballasts and bulky reflectors to ultra-efficient dimmable and spectrum tunable Light Emitting Diodes (LED) and Ceramic Metal Halide (CMH) all-in-one fixtures. The modern hobby and commercial cultivator now have the power to dial in spectrums specific to the plant strain they are growing. LED’s offer the tunability to go from a vegetative blue spectrum to a flowering red spectrum with a turn of a knob. CMH’s closely mimic the sun, provide the highest gram per watt, and even provide the coveted good UV wavelengths that fend off mold and mildew as well stimulate plant vigor and greater resin and terpene production. Choosing which technology is right for you depends on the size of your grow, how long you will be growing in the space, and your allocated budget.
The anticipated duration of your cultivation project is one of the most important factors to consider. Choose LED if you plan on keeping the fixtures for more than 5 years as the high upfront initial cost of LED fixtures will be amortized over a longer period of time. LED bulbs last 50,000 hours compared to 20,000 for CMH. If you are planning for obsolescence and want the greatest yield ROI within 1-2-year time frame, choose CMH. And even if you keep your grow space past 5 years, don’t worry, CMH’s provide a greater gram per watt due to their higher PPF and canopy penetration.
Let’s talk about the size of your grow. Because of the lack of overall canopy penetration, you will need to keep your LED lights 12-18” above your canopy. This could be a good thing if your ceiling height is less than 8ft and really need to factor in heat management. If you have a larger and taller space, using CMH technology is a better choice. Increased ceiling height allows for better heat management, better air-flow capability and more even light coverage for fuller and taller flower strains. LED lights put off very little heat and this can be good or bad depending on the size of your grow space and the climate at your facility location. How insulated your space is during winter months is crucial if you are operating in colder climates. Due to the lower heat output of LED’s, heat may need to be added to the grow room in colder months which will increase costs. CMH fixtures put off more heat than LED’s, but less heat than their HPS counterparts. This heat can be utilized to achieve the ideal temperature for your growing methodology, for example, if you are using CO2 injection.
Finally, everyone’s favorite factor to consider, BUDGET! The initial cost of an LED is 2 to 4 times the cost of a comparable CMH fixture. (see Table 1 below) LED fixtures, especially the ones that include the UV spectrum, are very expensive in terms of up-front cost. When it comes to power consumption and the power bill, LED’s only save the grower about 15% on the power bill compared to CMH fixtures. However, the LED grower will use less power for cooling, but that savings depends on other factors in the grow space. The additional cost a CMH grower will realize is replacing bulbs. You will be buying replacement CMH bulbs after 12-18 months of use. In addition, it is recommended that you change between the 4100K CMH bulbs in the vegetative phase to the 3100K CMH bulbs for flowering. Therefore, you will incur the cost of more bulbs utilizing CMH technology, but you will optimize your light cycles and extend the timeframe to replace bulbs.
In conclusion, each technology, CMH and LED, are viable to successful grows however they speak to different methodologies and business initiatives.
Choose CMH if:
- You need to maximize ROI in within 1-2 years
- You need greater canopy penetration for the strains you are growing
- Need the beneficial UV spectrum for maximum terpene resin production
- Need to maximize your gram per watt and flower quality
- Qualify for state rebates
Choose LED if:
- Have a long-term plan with current LED technology
- Need an exact spectrum wavelength to grow a specific strain
- Qualify for state rebates
- Yield quality and quantity are not paramount
48 Responses
What CMH lights would you recommend?
Dimlux 630 with square wave is an excellent start. Very reliable. Check it out on our website here!
Have u tried the 600w cmh that screws into the e40 fitting u can use hps ballast for them it’s a hortivision brand not many Australians know of the bulb still I’ve used them they work quite well they are 3000k.
I have a 315 cmh and I’m going to try auto flower for the first time, can I have my 315 and ran a red LED in addition to the 315? In a 5×5 grow tent
Yeah, you can do that. There is range in which a plant’s needs are best met. Adding more light may help marginally, but don’t expect wonders. Also, keep an eye on temperatures at the canopy. Let us know how it works out!
A 315w cmh is way too small for a 5×5 depending on the quality you want if u want a grade flower u won’t get it if u go the 600w cmh from hortivision that runs on a hps ballast u will do alot better but still you won’t get the 1000par you need around the edges I use a 90x90x200 the to run a 600w cmh with a massive reflector that’s 87×87 that has a cool tube the results are really good.
Tried a 315 cmh for a few runs. It’s better than HPS but for my space, I liked the LED much better. I run UBA/B with my led and it outperformed teh chm. New tech is not always better.
What was the wattage of the led in comparison to the wattage of the CMH?
Good question. We were forced to remove the charts from this article a while back. An LED company was not happy about it… and sent a letter from their lawyer to us.
If I remember right, we were comparing 1000w LEDs to CMH.
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A 315w cmh is way too small for a 5×5 depending on the quality you want if u want a grade flower u won’t get it if u go the 600w cmh from hortivision that runs on a hps ballast u will do alot better but still you won’t get the 1000par you need around the edges I use a 90x90x200 the to run a 600w cmh with a massive reflector that’s 87×87 that has a cool tube the results are really good.
What LED brand light do you use or recommend
false… there is no way that CMH gives better results than LED results per true watt. I get better than 3 grams per watt with my LED, and me being a fairly newb grower. CMH can’t touch today’s LEDs. Game over.
I get at least that with a CMH. LEDS need a lot more wattage to compare to lower wattage CMH.
You should get your facts straight before copping such an attitude and calling things false. And what “game” is “over”? We’re all just trying to grow a plant that you might benefit from cause you need to calm your self. You sound like an LED shill.
lmao. I love digging into the old threads and laughing at smug jacka$$es that are admittedly noobs making egregious claims. Bro ain’t pulling no 3g a watt as a noob and is likely lucky to be pulling that WET. I’ve been growing for 20 ears and my run ever was 3.86 lb per thousy from Super Lemon Haze and I vegged and topped it like a madman for 6 weeks before flowering the crop and then ran the full ten weeks to max them out using Tupur and feeding AN 4-6 times per day depending on my VPD and atmospheric conditions PLUS pumping in 1,500ppm CO² b the second week of flower and taper down with my temps by 200ppm and 3-5 degrees F weekly for the last 6 weeks so that in the ripening state, I was still handing them 600 ppm CO² and temps were 65 by day and 60 at night with 40% RH. Bros dyslexia kicked in. He meant three watts per gram. lol
My exact thoughts. Lol
That’s 100% Bollocks especially if you are truly running comparative wattage. Seen pro gardens under a 3000 dollar led set up running 1000w with added uv get destroyed by a 2x315w focal double end ballast. coverage of the 8 (from memory) led bars for his 3x3m tent covered the canopy fully. The focal cmh sat in the middle and doubled the results and the quality was hugely noticeable. Same drain to waste and same mother. Led are over stated. They work but they are no where near the best. Sun, Cmh or hps for results
I’m sorry, but you’re just wrong. There have been multiple controlled studies that saybthe exact opposite of what you’re trying to convey
not true I bet I out perform u with my cmh plus my terp % prob double yours and resin not even in same ballpark I have DE 1000w cmh and I have HLG 750R spec LED some say best led company in market for quite a while the HLG is yield is 30-40% less than the cmh I run cmh at 240v draw less than 4 amp and the difference I bill is 7.36% more for cmh and at 30,000 hrs on cmh still 95% effective plus I rotate 3 lamps during a cycle 4100k veg 3100k flower then last 10-12 days 10,000k massive UV like frosting a cake 9.5 out of 10 pick cmh flower I ve been growing for 17 years 7 commercial of the 17 I get my fixtures and 3 lamps for $398 each x100 units HLG are almost double rotating lamps I get several years a lamp never had a ballest go i have however had several drivers fail with a cmh u can touch reflector 10hrs in and wont burn u if short my partner went toe to toe on this he is an led nut the guys who say they get 3 g per on led are only doing a few plants and spending hours manipulating the plants to do that cured and dried???? bet not try doing that with a 100 or 200 your labor costs would out weigh production in red for sure
What led lights are you using?
Bs. Led more yield than cmh
What brand lights you use brother?
Your funny. Actually facts differ
LED better than CMH!??? You must be new to horticulture. As a 20 year growing veteran I had a true 1000 watt LED bars that could barely cover my 4×4 grow tent during flowering stage. I got 2 315watt CMH fixtures and it blows the LEDs out of the water. They are so powerful I upgraded to a 5×5 grow tent. I have around 600 pars at the edges and corners so i then use small LEDs around the edges and corners for a full 900-1000 par coverage during flowering stage. The only complaint is its a tiny bit more heat with CMH but not by much. You are truly an inexperienced newbie!!! LEDs are not superior in any way to an CMH.
Mito.les 3.5 gr par Watt des led est qu’une indication que tu as lus..je ne te crois pas..perso ,j’ai fait avec une led Samsung 301h 300w ‘et jai regretté ma cmh 315 en terme de rendement et qualité.. même variété même bouture, rien à faire..la cmh est bien meilleure question rendement
@bill Jones while your gram per watt is impressive a experienced grower with the right strain can get that with any of the lights available. I’ve been growing for 20 years and I use leds currently and while they are awesome at saving power etc I get no better gpw with using the leds vs cmh vs hps. For you to state your opinion as fact and say your fairly new shows your lack of experience. Fact is I use a very high priced led to get the same quality and yield I get with a cmh and or hps the difference is my overall cost of running multiple lights. Back to the comment of yield I’ve yielded more with hps and say Santa Cruz blue dream then I have with a solid og kush no matter the light being used genetics play the role as well as experience and quality of lights being used. The info you give is False hope for someone to say hey this amazon led is 100.00 it’ll out perform a 150 vivosun cmh 315 with a Philips bulb and I’m sorry that’ll never happen. Quality leds do yield close to the same as hps and cmh but everything is subject to the basics 1. Grower experience 2. Strain 3. Style (method of growing) 4. Co2 added
Sure, experience obviously matters but do a little research. Metal Halide has been proven multiple times to not provide more grams per watt, but also higher trichome production.
What LED do you recommend
Even though the fixture was a POS, the Grower’s Choice 1,000W DE CMH lmaps were the bees knees. I had m best runs under them until their cheap ass CHinese ballastcrapped out and one by one, the all started melting the the power cord socket on the ballasts. Never been more disapponted in my than losing my massive CMH lights. NOTHING touched them, Not HPS< NoT LED< and Certainly not flourescent or anthing else. Those thousy DE's were BANGERS but they just gave up on the big boys to keep on the 'Master Pursuit" series.
Would it be ok to have a cmh 230 watt Eye HID Lamp Ceramic metal halide in the middle of the two 600 watts hps lamps I’m running? I’m 4 weeks into flowering.
Yes, that works. Keep track of canopy temps, and you should be good to go.
led will not produce uvb,in any usable amounts go look lots studies on it,cmh with led is best cmh for the hole in leds spectrum
I’ve in my second run w LEDs ,after using CMH w HPS for a couple years
Growing a strain I’ve grown several times. Same batch of genetics. I’ve learned that LEDs take longer. I budding at 30 days or less w CMH. LEDs – I’m at 5 weeks and bidding has barely started. What’s up? Anyone?
Prolly worked this out in 2 years. But the led system is likely very low quality and lacks any usable spectrum needed for photosynthesis or simply you’re timer wasn’t correct. I.e smtwtfs= 6pm-6am but maybe one of the days has 13 hours or even 18 hours of light. Let me know the issue any how
I like leds for veg and cmh for flower
But also I have to be smart about what strains to grow in summer as it’s very humid where I live , apart from that it’s just obviously better in winter and I’ll usually just grow some big ass haze in summer
I use 630 double end cmh bulbs has anyone compared them to two 315 ? I’m wanting to add a few more lights can’t decide to stick with what I have or go to he smaller ones
“keep up the excellent work, I read few articles
on this site and I believe that your site is rattling interesting and holds bands of great info. I like leds for veg and cmh for flower
Does led grow light do any harm for human body ?”
Very interesting stuff!
I´ve been using both high end LEDs (Lumatek, Photontek) for 2 years now, and double ended CMH (lumatek) for 6 years.
Have been growing indoors for over 25 years. I have a 5 year degree in biology of systems.
So I have some experience.
Are LEDs hyped up? Yes, but probably do to growers going from old HPS to new LEDs, skipping CMH all together. It´s like changing your 1994 VW jetta
for a new Tesla.
Shops and manufacturers make a lot more money selling LEDs too, so you can find all types of reviews on the web about how great they are.
I would strongly recommend any newbie to start with CMH. Plants like it better. Less issues all around.
For LED fanboys I would recommend adding a small CMH bulb to your grow during the first 4 weeks of flowering. Keep the LED on but dimmed at 25% (about 200w of power draw) and the CMH at 100% (300w)
I´ve seen 30%-50% percent yield increase just by adding a 315W CMH to a 600W LED in a 5×5 tent.
i have 2.4 grow tent 1.5 wide cmh twin globes one end 8000w led down the other end 17 ounes under cmh and 29 under led light bang
I just brought my first 2 315 cmh lights they seem really good so far I may need some glasses. I have been a led and hps grower for afew years with both giving me good results. But I still use both of them I’m what you call a mongrel hahahaha but all seriousness. I have the 640w helios 6 bar led good light. I also have a 1000w led cant remember the name but good also but had to supplement it with more red spectrum kind of pissed me off as paid over a grand for it. Then I have 2 hps 600w digital ballasts and 1 400w mh. And now 2 cmh lucius 315watts I’m trying out I may get the bloom bulb on my next run. But because its winter I needed the warmer light for my tent which I’m running 2 inline fans both 200mm ones. 1 for input the other extraction with carbon filter and 2 oscillating fans clip ons inside hoping that’s enough. But if was to run a led I’d be battling the cold so was a better choice. And to be honest in the long run is better then a led to 50.000 hours and you cant change the bulb just buy a new one more like it. With cmh or hps there cheap just new bulbs really 60 bucks to 150. How much would it cost to replace your led bulbs I wonder.
Looks like there are a few people in the comments salty that they spent a bunch of money on LEDs that get outperformed my old school tech. Obviously experience and other variables can effect outcome, but there have been multiple research studies done that say metal halide provides better yields AND trichome production. Sorry you fell for the same old “newer is always better” bs, but to call someone a liar that has actual data driven research to back them up is just childish.
I have got Two 315sand I have LEDs I have been getting great product from the sun storm from hi par found the 3000k better than 4100kfor veg an bloom
I have got Two 315sand I have LEDs I have been getting great product from the sun storm from hi par found the 3000k better than 4100kfor veg an bloom .
LED lights are great they have come a long way and technology I remember.,
Just about around like 2014-2013 LED lights were still in there infancy stage I remember the old UFOs LED lights in the horrible blurple color oh gosh well that horrible but I say maybe a couple years
Remember a few years go by around about 2017 they started to get really really better in the technology
Kind have took a snowball effect because they came out well different companies came out with some killingly lights and I thought they were amazing myself and some of them do put off heat so there’s a lot of misinformation out there that same LEDs don’t get very hot well that’s not true electricity light diodes are produced heat remember that in the heat will build up maybe not as fast as I old fashioned HPS or MHS but the problem. The problem is LEDs are good but the new CMH have a coloring rendering index of almost 100% CRI and not only that cmhs they really penetrate through the canopy it’s hard to get that from even some of the best leads I’m sorry LEDs so neither one is better than the other it’s all about how you use the technology so before you or anyone trying to bash one technology for the other think twice cmh’s they penetrate really deep through a canopy I mean those suckers will give you a suntan you need to be really careful and protect your skin and your eyes when dealing with CMH lights and any other rights but especially with the ceramic metal hids. Yes these bumps is little envelopes I’ll give you a tan they will burn your skin or irritate your skin and your eyes you must be covered up and protect your eyes in any event never look at the ball of a CMH never look at any light unofficial that is and the cmhs there aren’t that bad they don’t give off too much heat but they give off enough but not to the point to where you wouldn’t be able to control it unless you have a large setup try the grower’s choice ceramic metal halide they have very good technology that doesn’t leave a spike in your electricity bill and has a soft startup there is a lot of technology and that companies balance don’t get me wrong I like the lights the LEDs they are great but in my opinion I have more dense solid cold colas with the CMH set up but at the same time I have a really cool LED light and it really rocked it was a 500 watt lead LED and it was to replace a thousand watt allied allied so yes you’re going to get very good penetration with these little bitty small bulbs and they are better than the 601 hps’s or 600 I meant and the thousand watt HID light those little bitty lights are so strong it’s unbelievable most of the
Bulbs are like double jacketed so you have the chemicals that the electricity excites inside of some type of glass or Crystal envelope whatever it is and that’s just any excites it and it gives off fairly clear like that you can see not yellow not purple almost like white white you can see very good with the 30 100 3100 k and the 4100k and then you got a 3100 for a red so you can meet your match these bulbs to come up with a spectrum not only that if you choose wisely you can daisy chain them but like a telephone cord and you can dim them down to whatever meet your need in this I said well turn the lights on and off for you and you can run to circuits so you can run around the room on edge one room on balloon off of one device controller they have a sign up and sundown which I don’t know if it’s necessary I use it just to keep on coming on with a little slow and easy not too fast and you can set them to them the lights for you if you reach or exceed temperatures that you dialed in so if you dialed in the temperature in the room to be 80° in the room heated up to 81°, the controller will dim the lights down as much as it needs to until the temperature is back under control and then it will slowly rev back up but you have to get the right technology leads are great they do good cmhs are great and they do good you get a little more heat but you get great penetration and a very good color rendering index if no one agrees with me could you explain to me why but like I said both technologies are
And it’s great to be able to pick and choose just depending on what you are trying to accomplish some circumstances you might want to run leads other circumstances . You might want to run your CMH fixtures it’s not that one is better than the other it’s how you use it it’s all about how you use the technology now I’m never going back to 600 HIDs and thousand HIV HIDs I mean you get more color spectrum of the CMH or the LEDs as long as you don’t get those cheap blurple lights but anyway it is great to use a light meter to give you a ballpark range of how close you need the fixture to your canopy but you can almost do the math and you can almost Intel without using I like meter some people say oh just stick your hand under there and if you feel it burning your hand then you need to back up so well that’s not a good practice to use to determine the height that you should have your balls from the canopy just start off high and just a little farther away then normal and ease up to him or sometimes they just grow into that zone and they want to keep it right there at that song not too high not too low especially when you start producing try Crohn’s it doesn’t take much to make them disintegrate so that’s something to think about and if you use CM ages try to look for a mom not only admits a UV spectrum and this will trick the plant into thinking that is getting a sunburn and produce more try crowns to protect it this is very true thanks for listening and reading sorry I was so long and boring have a great day
What if you mixed them? How would you configure the 630w to work with the modern LEDs
Has anyone ever used both 3k and 4k bulbs at the same time and red lights to mimic sunset/sunrise?
Absolutely love running 2 x 315’s in my 7×7’ space. The heat really isn’t that bad IMO. Helps actually, especially in the winter where I would have to really up my heating with LED’s. Appreciate the convo. Good vibes
Numbers given are averages to
Give an idea as to what is possible, on average. Every grow is different. So many variables. More than strain, experience and co2. Temp, environment, soil (less) it all plays a role. None of those are what gave me the best yield I’ve ever had. There’s more
To it than (this plus this equals that). Some things that really matter are never talked about because they won’t make the company cash.