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315Watt CMH Lighting: Specs, Coverage, Pics

Do you think CMH is a viable alternative to LED?

  • Yes

    Votes: 30 69.8%
  • No

    Votes: 4 9.3%
  • I need to read more.

    Votes: 6 14.0%
  • Isn't a Poll a sheep.

    Votes: 3 7.0%

  • Total voters


Well-Known Member
Thats an awesome comparison set up you have there geo.
Are you just running the autos at 12/12 with the 2 photo plants? Just because I thought autos are supposed to be 18/6 or above.

Hey Urbs, they sure do make plants grow healthy. Nice looking bud!

Im still playing with my cmh, trying to find their sweet spot.
I got some focal reflectors so next run should be good.
What tempurature bulbs are you using?
I see good results with ones around 3100K, mine is 3200K.
Was just wondering if people tried the 4000-4200K bulbs all the way through, and what resuls were like compared to my 3200K.

Just harvested....., 2 x 315w CMH,
9 plants in 20L pots, no enviromental controls, 4' x 8' tent....now drying tent..

That be an easy 2 pounds when dry. Got that last time in 10L pots, so should be a bit more than that I hope, for the extra 10L pot size each.

Happy Growing!
I've got the autos already above the surface, and soaking the photos now. I figure I will veg the photos for 8 weeks, and any autos left at that time can finish up while the photos do their stretching after the flip.

I will be letting the autos go natural, and LST the photos.


Well-Known Member
Hey @GeOMaTTiC , how did your autos go? Hopefully they loved the CMH.
My lights are on holiday for summer.
Dont forget to drop your CMH results and pics guys!


Well-Known Member
They are doing excellent.

One is a new strain to me from Garden of Green, GDPxGumberry

The other I've already grown under a Phlizon LED, NLxBB from Oasis genetics.

So far the NLxBB under the CMH is much bigger than the first round, but I can't yet fully confirm if the small plant was my fault, genetics, or the light. I assume it was the light, but I will be testing that theory out soon enough

GDPxGumberry on left, NLxBB is on the right, both are just a out 5 weeks old.

No training or defoliation, just some tucking of leaves when they were smaller.

First NLxBB was trained, and after seeing this beast, I want to try it training the next one. While it's pretty even as is, I'd rather keep everything level.


New Member
Hi All, First post on this forum. I'm running 2 x 315CMH in a 4x4 tent as I researched that one does a 3x3 tent so hence upping the lighting. Currently doing a GSC Auto grow. They are 4 weeks most started to head. They do vary in height a bit though which is confusing considering all are in the same soil, nutes etc. The higher ones are not as dense and internodes are quite spaced out. Others are closer spacing but not as tall. Time will tell...

My last grow was period SSH. Amazing results.
I'm a CMH convert for sure.


New Member
Isn't that what your supposed to do? LOL, Gee thanks for the warm welcome! LOL I have a long memory! LOL
There's another strain in front that needed "training" as it really stretched. There was 2 SSH behind this one. The SSH's were heavy yielders.

The Physicist

Well-Known Member
I recently upgraded to the Hortilux 315 CMH. I recorded the spectrum below compared to sunlight. Note they don't show the full range of the spectrum on the box. The Bulb extends all the way to 350nm and all the way out to 850nm giving a much closer sun like spectrum than any other bulb. I previously ran the Phillips 3100k but upgraded to the extra UVA and IR band energy.
Hortilux 315W:
hortilux 315 cmh.JPG

Sunlight Noon California:
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