CMH vs LED vs HPS

[exoticrobotic]

If it were purely a light intensity issue then the top buds would surely be ok in a led grow but for me the resin glands generally stay transparent to cloudy, hardly a shiny amber in sight.

 

[greencalyx]

Further, the pronounced vertical loss of light intensity in the vertical cultivation system resulted in insufficient photosynthetic conditions and crucially determined the direction of monoterpene transformation reactions in peppermint. The low light intensities led to unwanted high pulegone contents and triggered the undesired synthesis of menthofuran under all light qualities. Thus, the light intensities perceived by the peppermint plants are not suitable for obtaining peppermint oil of quality as specified by the European Pharmacopoeia.

Well no surprise they had insufficient photosynthetic conditions, look at the pfd they were using:


It's like they were going with the minimum value given here

 

[Lao Tzu]

Under LED I struggle to get the resin to mature to amber without the heads withering and shrivelling up.

The smoke needs more bass. It tantalises me with the 'here i am' but then decides to take me nowhere...

I have another smoke and it takes me one stop again.

It's clear many are experiencing the same issue and either A) don't care because the quality difference is subtle enough that they cannot notice it, or B) they were growing or buying avergage quality cannabis in the past, so the new quality is still a step up for them. This mostly applies to commercial outlets who are achieving good weight of harvest, which is the only metric along with THC that matters to them.

Add in money invested + ego and you get this stonewalled discussion on both sides.

I grew some Kryptonite Abusive x bubba under both cmh and leds.

The ones grown under leds were 6 months more mature than the seed plant grown under cmh as they were revegged and cloned.

The cmh bud was a woah moment. The high was immediate and rushy. The terps were plentiful, lime, pickled onion monster munch, swan vesta used strike pads, twiglets, sugar puffs and coffee, all in a long journey that was lip smackingly good, made you nod your head and exhale a relaxed mmmmmmmm.

The more mature led bud from that plant was nothing in comparison. very one dimensional in every aspect. The buds were drier in feeling, not as sticky and the terps had all melded into a diluted generic slightly musky lime.

There was little rush and sparkle to the high.

I'm starting to wonder if this is an issue of palates. For example, the average person would not appreciate the subtleties of fine dining and instead would insist that a cheaper hamburger is in the same stratosphere as a Michelin starred meal.

This may be a case of people literally not having the palate to tell the difference. Look at how many people still eat at McDonalds.

 

[goingrey]

I'm starting to wonder if this is an issue of palates. For example, the average person would not appreciate the subtleties of fine dining and instead would insist that a cheaper hamburger is in the same stratosphere as a Michelin starred meal.

This may be a case of people literally not having the palate to tell the difference. Look at how many people still eat at McDonalds.

It is interesting that rather than talking about differences and individual preferences it's a "universally better/worse" debate.

In the past HPS buds were considered to be lacking in effect by most due to the less-than-optimal spectrum of the light. But if that's what someone is used to maybe it's what they consider the best, the "just like momma used to make" effect.

CMH was generally considered an improvement but personally I missed that era. The equipment seems to be on sale at the moment so maybe it would be a good time to try it out. Though plasma would interest me even more but the price is very high.

 

[Sativafiend1973]

When I first started growing I started with blurple LEDs, I grew some decent plants that got me high and kept me there. I was told that hps was better so I purchased a 400 watt hps, and I used it for two years, I just recently went back to LEDs, at the same wattage as the hps and the results were staggering, I tried a cut that I used under hps and used the same cut under the LEDs, I can't say it was better or worse smoke wise but the bud was frostier and bigger, I got my money's worth and I don't even use the LEDs at full power, I was never a fan of LEDs and really thought they would not improve, I was wrong and glad I gave LEDs a second chance.

 

[GoatCheese]

Under LED I struggle to get the resin to mature to amber without the heads withering and shrivelling up.

If that happens then obviously your led light is too close to your plants

 

[exoticrobotic]

If only @GoatCheese

Irrespective of the distance from led to canopy i rarely see amber heads. Most are still cloudy/transparent well past 8 weeks. The few that have turned amber, actually i should say brown, look shrivelled. Not like the clear gold i am used to.

 

[Jaysways]

I’ve literally just chopped under LEDs and there amber , I’m chopping again on Saturday I will literally get the digital microscope out and show you amber trichs under LEDs

 

[GoatCheese]

I can get why COBs are better then traditional flat panel layout diodes, they mimick HIDs

Damn... Goatcheese I think your onto something here
Maybe intensity can't be added by same intensity sources as far as humans, but when you direct multiple sources at one spot like COBs do, maybe that will explain the difference in quality, as you are creating sufficient amount of light in 1 place for the plant to complete it's procceses fully.
Interesting... With better spectrum I can see it doing better somewhat

The thing is I don't believe this lab test cuz I smoked so much weed that's been in lab tests and got over 25% thc but was trash
Maybe it was hps maybe led but at the end what I'm saying is they shouldn't be trusted

If you smoked it and it was killer ok but going just on lab tests alone... Very hard thing for me to do

I don’t think people getting poor results/weak smokes with leds are imagining things – i think that something has gone wrong with their grow and/or they are using the led light the wrong way.

I think many people new to leds keep their lights way too close to their plants cause they go by what the light manufacturers tell them to do. And clueless companies like Mars Hydro seem to think that you can hang their lights much, much closer to your pants than you actually can in real life.


I’m a soil grower and i can’t keep my cobs much closer than 70cm to my plants – esp. during winter – or they will start yellowing and i only run my cobs around 25-30 watts each - but i have condensing lenses on them. Hydro/coco growers can hang their leds/cobs a bit closer to their plants than soil growers.

Leds/cobs will dehydrate plants (evaporate resin too?) if there isn’t enough distance between the light source and the canopy = leds create hot spots because the light beams are so concentrated and these will then heat up the plant tissue and dehydrate it.

When we see photos of those led grown plants that have almost no proper resin heads – as you have been saying and i’ve seen it too– i think this is because people push their plants too much with the wattage and/or have their led lights too close to their canopy ...as i suggested in the other thread months a go.

Have a good one, Snakey.

...and next time you’re gonna bloom plants under leds try to keep a good distance to your plants and make sure you get temps to around 27c-30c and good humidity %.

One more important factor is that you don’t point your circulating fan towards your plants cause this will make the dehydration issue even worse . i point my fan towards my cob lights and then the air will bounce on the plants off the tent walls. I saw noticeable improvement when i replaced a 20cm wide fan for a 15cm one and made sure the air isn’t blowing directly on the plants in my small tent.

 

[exoticrobotic]

Not so many do's and dont's with the hids/cfls

 

[GoatCheese]

If only @GoatCheese

Irrespective of the distance from led to canopy i rarely see amber heads. Most are still cloudy/transparent well past 8 weeks. The few that have turned amber, actually i should say brown, look shrivelled. Not like the clear gold i am used to.

I have seen evaporated resin glands on my plants if they got too close to my cobs – to me this points to a dehydration issue as is the yellowing plant tissue= the amount of wattage is too much for the plants to handle or the light is too close to the plants. This issue gets worse if the envirnment in your grow are is off – temps and humidity are too low.

Air movement in the grow area is another important factor - if a circulating fan is blowing directly at your plants it will make the dehydration issue much worse. I have my circulating fan blowing at my cobs not at my plants and this helps to keep them in better shape

 

[exoticrobotic]

I'm not sure that env factors temp, humidity, air exchange, wind damage can explain such a difference in the end product's high.

They weren't really present with either grows in any case.

I got larger yield from the leds by quite a margin achieving well over 1gpw. Cmh never got close but the cmh bud more than made up for it with the quality and depth of the high.

 

[bigtacofarmer]

I would guess a lot of it is related to leaf temperature. This is why plants prefer 82 to 86 degrees under LED and 78 degrees under HID lights. A few degrees can affect a do a lot to the plants metabolism. I think with HID you could get close to the right temperature and still have high quality results. And without the guaranteed leaf temperature with LED it makes getting it perfect even more important.

Another thing to consider is anytime you do something to make your plants grow faster. Such as more powerful lights or co2. You need to keep all parameters in check to compensate for the faster growth.

That's my non expert opinion.

 

[dimodz]

I would guess a lot of it is related to leaf temperature. This is why plants prefer 82 to 86 degrees under LED and 78 degrees under HID lights. A few degrees can affect a do a lot to the plants metabolism. I think with HID you could get close to the right temperature and still have high quality results. And without the guaranteed leaf temperature with LED it makes getting it perfect even more important.

Another thing to consider is anytime you do something to make your plants grow faster. Such as more powerful lights or co2. You need to keep all parameters in check to compensate for the faster growth.

That's my non expert opinion.

yeah that right we to our clients also is best perfomence coming if leaf temps have 27C° to have fast veg and higher quality as results.

 

[snakedope]

Cmon guys, ffs its not a haze comparison grow.

In my experience the 300w maxibright led lights i used never fully matured the resin glands, the terpenes were not as diverse and the resin stalks were thicker than the heads when compared to cmh.

We call that, All Neck No Head

It seems just plain wrong to think that leds don't have the required intensity to power some of these terpene biosynthesis pathways and potentially other pathways as the light seems very strong by my eyes and stronger than cfls which i've also had better results with.

It does seem strong, so does the parking lot lights, but in reality LEDs are not strong at all, they each make 250lm avg, the only way they are strong is when u add all your diodes on paper and total them, obviously, it doesn't work in real life.
So like HIDs and any other light source, when you put let's say 3 - 1w diodes each 200 lm, next to each other you will simply get 3 x 100
You won't get 300lm all of a sudden.
What these guys don't understand is that there is a difference in rate per sec of the source (intensity) and total light in space (ppfd)
And now your logic kicks in, you grew better with cfl you say, have you ever flowered with a cfl that less then 2000lm rating ?
I bet you didn't, I'll let u connect the dots alone

Well techniques like a well-trimmed even canopy or having light strips surrounding plants instead of just on top may be able to mitigate the issue. But do provide an additional challenge for the grower and, dare I say, may be more in the domain of hobbyists rather than commercial growers running big rooms.

It won't help nothing, the light source in question (LEDs) just don't have the intensity, do whatever you want, scrog, sog, he'll put them upside down like in the iss
Still won't help, they are built to veg things, not flower.

The paper made no claims of HID lights being any better or worse, for the record. Though better light penetration is a known benefit to them so they may be at an advantage.

It didn't say it was better, but after reading this what will you grow with ?

If it were purely a light intensity issue then the top buds would surely be ok in a led grow but for me the resin glands generally stay transparent to cloudy, hardly a shiny amber in sight.

I also believe there's more to this phenomenoa then meets the eye, the intensity cannot be ruled out as it's the biggest difference between LEDs and HIDs, but the procceses the plants go under it is still a shot in the dark
Your theory about the tops is simply because LEDs don't have the intensity from the get go, it doesn't matter which placement the bud site have.

It is interesting that rather than talking about differences and individual preferences it's a "universally better/worse" debate.

In the past HPS buds were considered to be lacking in effect by most due to the less-than-optimal spectrum of the light. But if that's what someone is used to maybe it's what they consider the best, the "just like momma used to make" effect.

Huh ??? Lacking ? Are you fo real ? Who ever claimed they were lacking ... The best bud I ever smoked was hps..
As Chunkypigs with his MH if he shares the same feeling about his lacking HIDs

I don’t think people getting poor results/weak smokes with leds are imagining things – i think that something has gone wrong with their grow and/or they are using the led light the wrong way.

Goatcheese I like you, but u also like many fail to understand LEDs inherit disability, no intensity ! So, it doesn't even matter where u place your lights, you don't have the juice.

I think many people new to leds keep their lights way too close to their plants cause they go by what the light manufacturers tell them to do. And clueless companies like Mars Hydro seem to think that you can hang their lights much, much closer to your pants than you actually can in real life.


I’m a soil grower and i can’t keep my cobs much closer than 70cm to my plants – esp. during winter – or they will start yellowing and i only run my cobs around 25-30 watts each - but i have condensing lenses on them. Hydro/coco growers can hang their leds/cobs a bit closer to their plants than soil growers.

Leds/cobs will dehydrate plants (evaporate resin too?) if there isn’t enough distance between the light source and the canopy = leds create hot spots because the light beams are so concentrated and these will then heat up the plant tissue and dehydrate it.

When we see photos of those led grown plants that have almost no proper resin heads – as you have been saying and i’ve seen it too– i think this is because people push their plants too much with the wattage and/or have their led lights too close to their canopy ...as i suggested in the other thread months a go.

Have a good one, Snakey.

You know what, in lacking of any new evidence about the nature of this light (that's why I blame it for killing plants up close) I'm gonna stick to your theory for now, it sounds logical to me, hot spots that the beams create, it fits reality also cuz when I put them higher back then and dimmed them to 70% the plants were much more healthier, it goes against any logic don't get me wrong, more light more good ... But this light source is just built in a way you can't put it up close

...and next time you’re gonna bloom plants under leds try to keep a good distance to your plants and make sure you get temps to around 27c-30c and good humidity %.

One more important factor is that you don’t point your circulating fan towards your plants cause this will make the dehydration issue even worse . i point my fan towards my cob lights and then the air will bounce on the plants off the tent walls. I saw noticeable improvement when i replaced a 20cm wide fan for a 15cm one and made sure the air isn’t blowing directly on the plants in my small tent.

Yep this is true but I never have fans on my plants.

 

[exoticrobotic]

I would guess a lot of it is related to leaf temperature. This is why plants prefer 82 to 86 degrees under LED and 78 degrees under HID lights.

I'm not sure something so drastic as change in high/terpenes i've experienced can be down to such a small difference in a minor environmental factor like a few degrees temperature.

Your statement does go someway in helping to explain why hids are easier to get consistent quality results though as at the height they are hung to maintain that 78 degree canopy temperature the plants are receiving the light at an energy they can use efficiently.

 

[bigtacofarmer]

I'm not sure something so drastic as change in high/terpenes i've experienced can be down to such a small difference in a minor environmental factor like a few degrees temperature.

Your statement does go someway in helping to explain why hids are easier to get consistent quality results though as at the height they are hung to maintain that 78 degree canopy temperature the plants are receiving the light at an energy they can use efficiently.

I'm not the one that invented plants so I can not adequately explain why. But everything matters. Ph, temperature, co2, humidity, water, nutrients, light and so on. It may be hard to believe but if you get all of these almost right then it's easy to explain if the herb is almost good.

 

[exoticrobotic]

This article shows cannabinoids/terpenes change with led
https://www.sciencedirect.com/science/article/abs/pii/S0926669019301086

Maybe the people that don't perceive a difference in high arent using cannabis for the same medical things i am...

 

[exoticrobotic]

I'm not the one that invented plants so I can not adequately explain why. But everything matters. Ph, temperature, co2, humidity, water, nutrients, light and so on. It may be hard to believe but if you get all of these almost right then it's easy to explain if the herb is almost good.

For me, when everything is the same except the light it is easy to explain why the herb is almost as good.

I am aware though that led herb might be better for other people whos bodies utilise different parts of the plant's chemicals.

 

[goingrey]

It didn't say it was better, but after reading this what will you grow with ?

Yeah it's a good question. I have grown with both HPS and LED and had results I would have been totally satisfied with EXCEPT after growing a couple of clones on my windowsill and having them turn out more to my liking than under lights it's hard to not believe in room for improvement. Will it come from CMH or LEP or improved LEDs that is to be seen.

Huh ??? Lacking ? Are you fo real ? Who ever claimed they were lacking ... The best bud I ever smoked was hps..

Everyone was looking into MH or fluorescents or anything to improve quality back in the day. Well not everyone but it was a thing, especially with sativa growers. Here's one 40 page thread, one of many just the first one that came up..

MH vs HPS in bloom

its been talked about to no end but Ive yet to see it done.... easy is it seems? Ive heard all about MH gets you more resin and less stretch etc etc but personally haven't seen the proof? my last few runs in my 2000w grows i have been starting to use 1 Mh bulb in the bloom phase after 5 wks to...

www.icmag.com

Maybe this has been posted already but it's pretty interesting, 260W LED vs 315W CMH side-by-side with clones.

LEC vs LED Grow Lights: Side-by-Side Cannabis Grow Journal | Grow Weed Easy

by Nebula Haze This grow journal from 2020 features two indoor cannabis gardens that are identical except for one thing: the grow light! See a match-up between LEDs vs LEC grow lights. If you’re unfamiliar, LEC is a brand name by Sun System. LECs are also known as CMH grow lights. I have to...

www.growweedeasy.com

LED gave higher yield/W and higher THC content. CMH gave higher terpene content.

Visually the buds look really similar (yep, CMH trichomes also have the long stalks).