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CMH or HPS during flowering

K

kronicundrum

Hello all.

I have been growing with CMH for the last 2 years, and all has been great. I am averaging 550-650 grams with a 800w CMH setup (soil). But as I am finishing my 4th batch I am noticing it took an extra 3 weeks to flower, and I am getting about 80% as much weed as my first run. So my bulb is loosing power, and it time for a new one.

So my question to you fellow ICmager's is which light is better for flower, HPS or CMH?

I know that CMH runs cooler, has a better spectrum, and is way better for veg, but what about flowering?

I have noticed more leafy bud with CMH, and after 18 hours of harvesting yesterday, I would prefer less leaf to trim off the bud. They are still very nice so I am not complaining, just alot of work.

37812final_3-thumb.JPG


And isnt HPS supposed to produce more packed colas? I am not complaining with CMH, I get nice weed, but I simply have never grown with HPS so have nothing to compare to.


What is the best flowering bulb I could get for a 400w HPS ballast? A link would be appreciated.


Also I just use fans right now, how much hotter is HPS? I dont have an active light cooling setup, and dont want one.


Thanks!!!
 
K

KMK0420

kronicundrum said:
Hello all.

I have been growing with CMH for the last 2 years, and all has been great. I am averaging 550-650 grams with a 800w CMH setup (soil). But as I am finishing my 4th batch I am noticing it took an extra 3 weeks to flower, and I am getting about 80% as much weed as my first run. So my bulb is loosing power, and it time for a new one.

So my question to you fellow ICmager's is which light is better for flower, HPS or CMH?

I know that HPS runs cooler, has a better spectrum, and is way better for veg, but what about flowering?

I have noticed more leafy bud with CMH, and after 18 hours of harvesting yesterday, I would prefer less leaf to trim off the bud. They are still very nice so I am not complaining, just alot of work.

37812final_3-thumb.JPG


And isnt HPS supposed to produce more packed colas? I am not complaining with CMH, I get nice weed, but I simply have never grown with HPS so have nothing to compare to.


What is the best flowering bulb I could get for a 400w HPS ballast? A link would be appreciated.


Also I just use fans right now, how much hotter is HPS? I dont have an active light cooling setup, and dont want one.


Thanks!!!
Click to expand...


From the *general* consensus, CMH is "okay" to flower with, but HPS is preferred (yield reasons)..

i'm currently vegging some under a 400W CMH, but only plan to keep it for the first week of flowering, then switch to HPS the rest of the way...too many people said their yields were down with CMH.
 
Pinball Wizard

Pinball Wizard

The wand chooses the wizard
Veteran
I liked my 400 HPS Hortilux and I liked my 400 CMH though vegging and flower. About a foot shorter with CMH bulb. All other things; about equal.

I don't know what you can do with this information?..but, there it is....
 
K

kronicundrum

If bud yields are about equal, i would stay with the CMH for heat reasons.



How much hotter is a HPS bulb compared to a CMH?
 
K

kronicundrum

Pinball Wizard said:
I liked my 400 HPS Hortilux and I liked my 400 CMH though vegging and flower. About a foot shorter with CMH bulb. All other things; about equal.
Click to expand...


So the CMH produces just as much bud in flower as an HPS? I was kinda hopping HPS would be tighter buds and produce alittle more.

Anyone?
 
hoosierdaddy

hoosierdaddy

Active member
ICMag Donor
Veteran
I have grown the same strain under both, but not a fair comparison in watts.
I'm not convinced that HPS produces any better bud than the CMH. I'm more leaning the opposite. All the buds I have grown with the CMH seem to have far more swollen calyx' and resin output seems more. (shrug)
I do know that the CMH has more of what a plant likes than a HPS does, and in a much wider ranging spectrum.
I feel many who think CMH produces leafy bud may well be correct, but I also feel that the buds are also increased. More leaf doesn't equate into less bud...and it makes more sense that there is more bud as well.

CMH sure works well if it's colors you are after, and HPS can't compete there.

Ever see a seedling stretch out until it has almost no stem left? Or a plant that gives crazy stretch when thrown into 12/12? The plant is in need of more light. It has the natural ability to go search for more of it when it senses it's lacking.
Plants definitely stretch out more when put into flower with HPS than they do with CMH. I suspect that the plant is trying to tell us something.
 
K

kronicundrum

hoosierdaddy said:
I have grown the same strain under both, but not a fair comparison in watts.
I'm not convinced that HPS produces any better bud than the CMH. I'm more leaning the opposite. All the buds I have grown with the CMH seem to have far more swollen calyx' and resin output seems more. (shrug)
I do know that the CMH has more of what a plant likes than a HPS does, and in a much wider ranging spectrum.
I feel many who think CMH produces leafy bud may well be correct, but I also feel that the buds are also increased. More leaf doesn't equate into less bud...and it makes more sense that there is more bud as well.

CMH sure works well if it's colors you are after, and HPS can't compete there.

Ever see a seedling stretch out until it has almost no stem left? Or a plant that gives crazy stretch when thrown into 12/12? The plant is in need of more light. It has the natural ability to go search for more of it when it senses it's lacking.
Plants definitely stretch out more when put into flower with HPS than they do with CMH. I suspect that the plant is trying to tell us something.
Click to expand...

Ty Hoosier, you have persuaded me to buy another CMH bulb. I am deffinetly happy with what it has given me, but have never tried HPS so I was wondering.
 
K

kronicundrum

asde said:
1x600w hps can replace your 2x400w cmh without loss in yield!
cmh is only best for small grows
Click to expand...


I got 630 grams with 800watts of CMH, show me 1 s 600 HPS that can do that with 8 plants.

asde I suspect you talk before you know alot.
 
A

asde

Member
you gotta be kiddign me•••

there are dozens of reports on the web having results over 1g/w with 1x600w hps, for sure, for low power setups cmh is the better choice because of the way higher efficienvx but at high power bulubs hps leads at least from whats easily to get on the market
 
hoosierdaddy

hoosierdaddy

Active member
ICMag Donor
Veteran
asde, there are those who have actually used both, and still on the fence about HPS being superior to CMH.
It's easy to rear back and state an opinion. To back it up a bit harder.

I think it is pretty much a matter of consensus in the horticulture community that the plants thrive best with a mixed spectrum of usable light. Similar to what the sun produces.
When we look at the specs, it is clear that the CMH bulb is providing a far greater range of spectrum, of usable light, than any HPS. Couple that with the fact that the CMH produces in the UV range, where the HPS does not, and it seems like a no brainer.
I prefer to experiment and find out for myself what I like best, and what is producing the best quality buds for me. Some may want fat buds as their model for best quality, but perhaps at the expense of resin, and ultimately buzz quality.

I know for sure I won't listen to someone who spouts off an opinion without so much as offering up why they formed it, or any other sort of backup. I figure they are just like so many other dimeadozen internet parrots. (shrug)
 
A

asde

Member
maybe you can show me ANY grow report using 250/400 (or higher) watt cmh and getting close to or even over 1g/w?
from my theoretical pov cmh with 400w got not even a 0.01% chance to compete vs 400w hps when it comes to cannabis yield, 250w may be equal, lower cmh dominates, higher hps dominates..

from my practical pov im using an 70w/150w cmh and used hps before and cmh is not just on par, cmh dominates (especially the 70w is superb)
i cant tell anything about 250/400/600w grow practically but others did with reports and tbh the theory isnt proven wrong.

tbh were on such a high level of knowledge when it comes to absorption/quantum efficience(/signal function), if in theory a 400w cmh is yielding 20% less, in practical setups its not far from the theory!! if your really after cmh wait some month or invest the 5x price right now to get on same lvl as hps - theoretically.!!
 
habeeb

habeeb

follow your heart
ICMag Donor
Veteran
CHM just for the fact you can see your plants "true color" unlike under a HPS.
 
NorCalFor20

NorCalFor20

Smokes, lets go
Veteran
I have flowered with both, i prefer the HPS - CMH tends to have leafier buds.

That said, I think CMH and HPS should be used toghether....

for example...

if u are growing with 400w'ers i would use cmh during veg, then also use first week 1/2 2 week of flower, then switch to HPS during flowering and Finish the last week with the CMH.

That, in my opinion is how i'd do it if i were still using 400w's

When 1kw CMH comes out i will go back to using my 2 week beginning of flowering with cmh and finishing last week with cmh...

my reasoning behind using it the first two weeks is it reduces stretch almost to nothing. HPS good for fattening up buds, building flowers- stacking calyxs but throw in the cmh for last week of flower and it will make the trichs really come out... (maybe the maturation of the plant, only grew 2x with 400w's)

I would do it the same way again if i were still using 400w's

some of u may decide to use the cmh like i said first 2 weeks i can prove that will eliminate more stretch but the last week with CMH is experimental im not sure weather it makes a positive difference or not but i'd imagine that the spectrum benifits the THC production in the end phase.... As for HPS it builds tighter, denser buds for me when used during flower than if you use cmh the whole time.
 
S

stke_fingas

Member
i'm with norcalfor20, i still grow with a 400w and have done exactly what he has said. cmh for veg and 2.5 weeks of flower. i'm about to change the bulb out tonight, back to the cmh for the last week of flower. my last run i used the cmh the whole time and didn't really like the results, very nice no doubt but not dense nugs like with hps. the calyx's were very swollen and covered in trich's so i'm hoping that they will mature my fat hps built cola's in the last week.

i'll report back in a week to let you know how it turned out.
 
L

luminousone

New member
I've been lurking and learning for a while, but created an account just to chime in here.

In case anyone is wondering about possible yields with full cycle CMH, read on.

I use two 315w CMH bulbs in each 5x5 tent. I use only CMH. My fixtures are open and unvented. I have a few of these set ups. In each tent, I run 6 15 gal pots, all organic living soil.

I yield +- 2 lbs per run. This works out to be better than 1g/w (1.37g/w, if each 315w bulb is actually using 330w).

It's beautiful light - like mini-suns.
 
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