More Lumen = more THC? I think not

Hey guys,

last night I chilled at a friends house and a fellow grower and me got talking over some blunts.

He said that the amount of Lumen actually determines how much THC the plant can produce. For example he said that with my 400W HPS I will get somewhere in-between 16-18% THC and with 600 and 1000W the same strain (obviously only if it CAN go that high) would produce 18-23% THC.

The guy had been growing for like 2 years and I didnt know him so I wasent going to argue (my first grow) but it still kinda smells like bullshit to me.

Yes I know that lighting is the most crucial variable in growing and that the sun for example produces "better" weed because the spectrum of Cannabanoids are more varied or something. Still I find it hard to believe that a LSD plant under 400W would only produce 18% THC which is ok but not what LSD is.

Feel free to discuss either way; dont forget that if you make a claim you should back it up with some evidence (no flame wars in my threads )

I agree with you. There's several different variables. Strain, nutrients, spectrum, temp, humidity, air flow, co2, etc... Lumens are irrelevant. Lumens .by definition is visible light. Plants use very little visible light. Infrared and UV-b spectrum will form more trichs.

Actually I have been thinking some more about the topic and I think I know why he made this claim. His first grows were under a 400W but he only grew "bad" strains. Not bad bad strains but hardcore mainstream commercial stuff like Big Bud and I forgot the second 1. I am not shure how much THC Big Bud has but I think its quality over quantity with it right? He then upgraded to 600W and grew good stuff like Super Silver Haze and Agent Orange.

Pretty shure this is the explanation, happy I did my research on strains and Im growing NYC Diesel and Sour Diesel. Although this is not perfect, I think I will go for a really Indica Kushy strain for the "sedated" feel and get a nice strong upbeat sativa for the nights im out this is off topic though...

ViennaReview said:

Actually I have been thinking some more about the topic and I think I know why he made this claim. His first grows were under a 400W but he only grew "bad" strains. Not bad bad strains but hardcore mainstream commercial stuff like Big Bud and I forgot the second 1. I am not shure how much THC Big Bud has but I think its quality over quantity with it right? He then upgraded to 600W and grew good stuff like Super Silver Haze and Agent Orange.

Pretty shure this is the explanation, happy I did my research on strains and Im growing NYC Diesel and Sour Diesel. Although this is not perfect, I think I will go for a really Indica Kushy strain for the "sedated" feel and get a nice strong upbeat sativa for the nights im out this is off topic though...

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Strain is the main factor yes.
NYC Diesel is a Soma strain. You can't go wrong with anything from Soma. I like his lavender and Soma A Plus. I used to do Lavender back in the day. I just sexed an A plus and its a female wooot woot

Light/ Lumens actually degrade thc %
That's where the 48hr before harvest method originated from./

As I understand it the plant produces resin at least in part to protect it from drying out. As THC is produced with and contained within the plant resin then to me it makes some sense that a bud that was grown under harsh light may contain more resin by weight relative to fiberous plant matter, and thus more THC, than a plant that is grown under a milder light. Going by nothing other than the pictures people post of their finished crops it would certainly appear that those growing with high-wattage HPS lighting seem to produce 'frostier' buds, so I think it reasonable that a plant growing a 400W HPS may produce less resin than one grown under 600W. The 'frost' is a reasonably good visual indicator of resin production.

Lumens are not a good indicator of the light spectrums useful to the plant, but they are a good indicator of the relative light intensity produced by different lamps of the same type. If you're only comparing low-wattage HPS with high-wattage HPS then I think it reasonable that the lumen rating would be good indicator of the relative light energy produced and thus perhaps resin production.

Lumens have nothing to do with what thc percentage your plants will be.

if you notice (when you buy beans) it lists the thc content along with the description. it doesnt say, "20% thc IF you use a 1000w light" its just 20%. how much thc a strain is capable of producing is dependent on the GENES not the lights.

Lights help produce MORE/BIGGER buds. obviously a 1000w will yield more than a 400w but the quality shouldn't be any different if everything else is the same.

THC content is strictly determined by genetics nothing else. Everything else determines yield not THC content

I think it's worth pointing out that lumens are indexed to how bright a light is to the human eye. The eye's sensitivity spectrum aligns rather poorly with a plant's PUR (photosynthetically usable radiation) spectrum. A max-efficient grow light will put out a PUR-shape spectrum which, with its saddle in the yellow and green (wavelengths where the human eye is best) is low in lumens. cn

He said that the amount of Lumen actually determines how much THC the plant can produce. For example he said that with my 400W HPS I will get somewhere in-between 16-18% THC and with 600 and 1000W the same strain (obviously only if it CAN go that high) would produce 18-23% THC.

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On its face that's definitely false.

To the extent that absolute lumens matter, its has to be lumens per square foot of garden space, which is a better reflection of how much light a given plant is actually getting. The amount of absolute light any plant is going to get is going to depend on the amount of light put out by the bulb (ie its wattage), yes, but also the size/surface area of the plant!

Putting it differently, I could grow one small plant under a 150 watt hps, and it could receive more absolute light (lumens per square foot of growing area) than a much larger grow under a 400 watt hps that has more plants spread out over a larger area. There is no absolute rule that says that a plant under a 1000 watt lamp is actually getting more light than one under a small lamp. . .that's going to be dependent on the exact circumstances of the grow, including distance of the plants from the lamp.

In terms of things that affect potency, obviously strain is a not only a major factor, its probably THE most important single one. Growing conditions will matter (quality/quantity of nutrients, amount of water, hours of light/darkness, etc). Light SPECTRUM also matters. . .some spectra are going to be better for producing THC than others. Ultimately, there is a maximum amount of THC any plant can produce, up to its genetic potential.

But lets say we held those things constant. Lets say we raised two otherwise identical plants (ie clones) in the same hydro mix, with the same nutrients, for the same length of time, using the same type of light bulbs. The only difference will be that one gets 60 watts/sq.ft, and the other gets 80 watts/sq.ft (say by adding one more light bulb to the setup with the second plant).

Would the plant with more light/sq.ft put out more THC?

I think its not really debatable that up to a point, more light equals a larger plant. It would have more bud mass, and probably tighter/denser buds as well. So in an absolute sense, of course, a bigger plant will contain more THC than a smaller one.

The real question is, will this bigger plant have a higher THC *concentration* than the one that was more poorly lit?

I don't know the answer to this. It possible that this is true. . .more light = higher THC concentration, but its also possible that there is a bell-curve, with more light yielding more THC up to a point, then more light than that yielding LESS. Its also possible that there is a plateau effect. . .more light will yield more THC up to a point, beyond which it doesn't make any difference. I suspect that this latter is probably the answer, but I don't have evidence to prove it. .

bertiswho said:

THC content is strictly determined by genetics nothing else. Everything else determines yield not THC content

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That is only so accurate. Genetics set the limit on how much THC there can be, but a poor or sub-par growing environment, growing problems, errors, etc. will result in the full genetic potential not being reached.

Oh, one more thing.

Nobody really knows for sure what THC is "for" (ie what it does for the plant).

Some believe its a "sunscreen" to protect the plant from UV radiation.
Some think (as above) that it protects the flowers from drying out.
Some think the sticky sap is just to entrap (or attract) insects.
And there is always the "God made it for humans to get high" theory. A more evolution-friendly way of putting this is that the psychoactive THC evolved to encourage animal life to spread the plants pollen and/or seeds.

The point is, if either of the first two things are true, it might stand to reason that plants will actually put out more THC under adverse conditions. In other words, to get maximum THC production, maybe what you need to do is under-water your plants, and expose them to extra UV light.

Now realistically, years of selective breeding of high THC strains probably means that these plants will be putting out max or near-max levels of THC regardless of environmental stressors. They're genetically "programmed" to think that they're being bombarded with UV all the time (or drying, or whatever stimulus makes them put out THC). So again, we're really back to genetics as the prime determinant of THC production.

cannabineer said:

I think it's worth pointing out that lumens are indexed to how bright a light is to the human eye. The eye's sensitivity spectrum aligns rather poorly with a plant's PUR (photosynthetically usable radiation) spectrum. A max-efficient grow light will put out a PUR-shape spectrum which, with its saddle in the yellow and green (wavelengths where the human eye is best) is low in lumens. cn

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This is entirely true, but it doesn't really address the question of whether more light (even photosynthetically useful light) yields higher THC concentrations.

As I just posted, I'm just going to throw out for argument's sake that its entirely possible that the conditions optimal for THC production might not be the ones optimal for plant health and growth. Or more likely, the two factors might be somewhat independent of one another.

I'd tell that fucker to pound sand and tell him to come on over to RIU and say hi

You're right; I see that was ot.
Imo you propose an interesting question for a research grow. That grow would have to be deliberately non-commercial however, and the researcher would have to have an informed plan for which env. factors to vary. I do hold the unscientific opinion that environmental stresses/triggers won't have a large effect. If they did, we'd have many more unsuccessful or "wtf? My bud is hay!" results. Fwiw. cn

massah said:

I'd tell that fucker to pound sand and tell him to come on over to RIU and say hi

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Just what this site needs .................... another lost ball in the tall weeds.

i wouldnt put too much stock into what someone tells you on the street that "grows" anyway.

just the other day i had to listen to some dumbass go on for 20mins about how theres a secret "formula" to grow mj. i nodded and listened but it was more than obvious the guy was a moron.

id trust the ideas of those on a forum like this (who obviously are closer to being experts) then that jackass

lol hes wasent a stranger. I was at a good friends house and he is a friend of that dude. My friend knew we both grew so we talked a bit.

Brick Top said:

That is only so accurate. Genetics set the limit on how much THC there can be, but a poor or sub-par growing environment, growing problems, errors, etc. will result in the full genetic potential not being reached.

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my fault, i should of said maximum THC content.

duno, it seems the plants i grew under straight fluo were better than the ones grown under straight hps. (lots less buds of coz)

not alot better, but smell more pronounced and better and somewhat more potent (though not really more than a bit, more the smell)

couldnt state this for sure though.

but i added some 6500k 23w cfls, 3 of them to the grow now (600w hps) and allready i think this grow smell better than the last one straight hps (and the one with 3000k t5 added)

same strains.