12/12 18/6 Who decided that???

So I read in Ed's book...you all know him, right? It says...but I'm not quoting...when him and his author/partner wrote a book back in the day, they decided to condense all the info regarding where all the different species of Cannabis grew, they saw that all would flower if given a 12/12 cycle. So some species grew better with more light and some species grew better with less. So 12/12 was just accepted. It became a standard. Anyway, that's what I read. Not that Ed started it but I think he helped.

dannyboy602 said:

So I read in Ed's book...you all know him, right? It says...but I'm not quoting...when him and his author/partner wrote a book back in the day, they decided to condense all the info regarding where all the different species of Cannabis grew, they saw that all would flower if given a 12/12 cycle. So some species grew better with more light and some species grew better with less. So 12/12 was just accepted. It became a standard. Anyway, that's what I read. Not that Ed started it but I think he helped.

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I have no idea who Ed is or what book you are talking about but thanks for at least making a comment that makes sense. Someone read this book and told us about it and we all followed like good sheep do without question

faller200 said:

I have no idea who Ed is or what book you are talking about but thanks for at least making a comment that makes sense. Someone read this book and told us about it and we all followed like good sheep do without question

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Not exactly without question, if someone tells you 12/12 and you try it and it seems to work -- wouldn't you accept it as fact and then tell others the same? People do experiment with all sorts of grow parameters, but generally folks want reliable results and don't have the time or money to tinker around. You go with what others tell you, and stick with what you know works.

Now that you are questioning it, will YOU take the time to find out for yourself? I won't blame you for being part of the flock, I too would rather just get my expected results and get on with the next garden.

Ed Rosenthall is an author. His books are available on Amazon. He goes through a lot of what you're wanting to know but it's too much to type man sorry.

faller200 said:

I have no idea who Ed is or what book you are talking about but thanks for at least making a comment that makes sense. Someone read this book and told us about it and we all followed like good sheep do without question

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You mean like everything else you've been taught in your life? You read it, you learn it, you accept it. If you doubt it then you challenge it. You use logic and reasoning. You perform scientific experiments and you observe and study the results. If you want to come up with a hypothesis that 11 hours and 54 minutes and 19 seconds is the ideal amount of darkness for all MJ plants then go right ahead.

Or.... you can go with the information that has been gathered by thousands of growers over decades, pumping out millions of plants with reliable and reproducible results.

dannyboy602 said:

Ed Rosenthall is an author. His books are available on Amazon. He goes through a lot of what you're wanting to know but it's too much to type man sorry.

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Thanks sounds like a good read I'll check it out.

I feel like everything I've read about commercial growing they use 24/7 lighting on veg and 12/12 for flower. That's good enough for me. If the pros do it that way, they probably aren't fucking up their livelihood. And since mary jane doesn't have a nervous system, I don't see why she would need time to sleep other than the light schedule telling her to flower.

You know I didn't mean to get every one so worked up over this. You have all missed the point here. 12/12 and 18/6 started for a reason WHAT!!!! is that reason???? So far none of you have been able to factually answer that question. and I have yet to find an answer online. It's just a question. A question that seems to not have an answer.

faller200 said:

You know I didn't mean to get every one so worked up over this. You have all missed the point here. 12/12 and 18/6 started for a reason WHAT!!!! is that reason???? So far none of you have been able to factually answer that question. and I have yet to find an answer online. It's just a question. A question that seems to not have an answer.

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Are you not bright? It started because it's the balance of light and dark that makes a plant grow how you want. 18/6 is more light than nature, meaning more photosynthesis. 12/12 is because it takes at least 10-12 hours (depending on strain and genetics) of darkness to trigger the buildup of hormones that tells a plant to flower.

This is not rocket science. It's how every agricultural crop has been grown since Neolithic Asians first planted wheat over ten thousand years ago...

I will say it one more time 18/6 and 12/12 are not possible in nature. Therefor it was not done 10,000 years ago.

Fertilizers weren't made from chemical salts in factories either, yet they work...

Still no answer to the question.

Wow.. you are trolling.

Good luck getting your answer. Nature isn't perfect. Everything you eat and drink today has been modified by man in some way to produce more, taste better, be healthier. Cannabis is no exception.

I believe ed rosenthal was the first to pen this light timing

u no what fuck this guy and his quest for the perfect answer .so many ppl have answered ur fucking question and ur only responds is still no answer so fuck u and ur perfect answer fucking troll . stay high ppl!!!

I guess I'll throw my answer into the ring...People have chosen to use these times "18/6 and 12/12 because trial and error (which has been pointed out by many on here) has proven good results for most strains...Reason being your growing indoors...now once you accept that, you should know there's no possible way to really mimic outdoor style growing...The benefit of growing indoors is to create your own personal environment (however lighting cycle you choose, co2 you choose, nutrients etc etc...) getting back to the point here...these times are great because of the fact that you could never get sunlight for 18 hours outdoors, thats the whole point here, indoor growing is all about creating the most beneficial environment for the plant. Thus giving a plant more light than it could ever get..you'll never get 7 to 9 weeks of straight sunlight outdoors either lol...the 12/12 is a consistent light dark period to control exactly how your plant is going to be forced into flower and stay that way..sure you could give a plant 11 or ten of darkness but that will force maturity to the buds. Another quick point (tired of typing lol) is 18/6 after trial and error "which is in most grow books as facts" is the best ratio of light to dark to get the best root system...which in my opinion is by far the most important factor towards a plants health, size, and ending yield... 24/7 your plants will grow fast and lush but with the least amount of root growth, 18/6 will give a decent speed of foliage growth and root system, while 16/8 will give the most roots but a smaller foliage...at the end of the day its ALL about your own personal grow space and what your trying to achieve with what you have to work with....

sorry meant to say " 11 or 10 hours of LIGHT" will force maturity on buds

cacamal said:

I believe ed rosenthal was the first to pen this light timing

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Thanks I have never read any of his books but like I said eariler sounds like a good read. What Title do you recommend?

be nice...
...and yes...i'm gonna be trimming and getting high all day. it's what i do.
here's a pic of what i'm making today. it's a sour diesel chandelier.
sorry i couldn't answer to OP's satisfaction. I don't pretend to know everything.
i do make nice buds however. and for this i'm paid handsomely.


Marijuana Growers Handbook is a compendium of his earlier stuff and some newer technology, like LED's in there too. A very nice nute def and nute toxicity part with pics. The chapter on light is a favorite...peace...gotta trim now...

Im doing a 7/12 light cycle to force the plant to finish faster(in theroy a 8 week strain should finish in 6ish weeks) I know yield will be affected but hey I like to experiment