24/0 18/6 sex, true or false or just plain luck?

I took 25 seeds and sprouted them all seeds off the same mom. put 10 seeds in 24/0 light sced and 10 under 18/6 light sced, all same nutrients conditions lights,etc only difference is light sced..after vegging them for 3 weeks, i put them all into 12/12..the 10 that had 24/0 light sced got 5 males and 4 females and 1 herm..the plants that had the 18/6 light sced i ended up w/ 7 females and 3 males..is that proof that light sced and the right conditions provide a better female to male ratio? or is it just plain luck of the draw seeds? ive done this test 2 times now, both times i had more females out the 18/ 6 light sced..last run i got 6 females and 4 males under 24/0 and 8 females and 2 males under 18/6..All in 4x4 rock wool flood n drain table w maxi grow by gen hydroponics, and 200 watt cfl light w 6400k, room temp 72 degrees w a ph of 5.6-6.0. then flowered under a 400 watt hps w maxi bloom same ph, same room temps, etc...Now, does this prove seeds determine their sex by enviroment or has it just been plain luck that 2 times i ended up w/ more females under 18/6????any body have anything to add or has anybody else done his test??

Probably just luck of the draw, I've heard/read about the environment (temps/humidity) potentially controlling sex, but I've never seen a proper study/paper stating it, nor anything related to shorter light periods, just internet talk.

That said, ever since switching my seedlings/clones from 24/0 to 20/4 light cycle I've popped 9 of 10 females from regular seeds. And they ARE regular seeds, 8 of the 10 are my DIY's and I didn't feminize them. Hmmm..... don't want to start yet another internet theory DISCLAIMER: JUST A THOUGHT: some dark period = increased fems? Would love to find some science/data on this.... The 10th is still not sexed, could be fem too, a late bloomer that I haven't been able to read 100% yet.

I have +95% success with jiffy peat pucks, cool temperatures germinate at ~65
neutral ph ~7.0 water - moist not wet
and a full 24 hours of dark after breaking the surface.
a couple of different factors to consider

mmmmbrownies said:

I have +95% success with jiffy peat pucks, cool temperatures germinate at ~65
neutral ph ~7.0 water - moist not wet
and a full 24 hours of dark after breaking the surface.
a couple of different factors to consider

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Oh yeah I'm sure there's a lot more. I followed a thread on this environment/temp theory on here, interesting but inconclusive. I posted on that thread that my environment for this 9/10 fem streak I'm having have been more in the 76-80F/65RH. Only real change during that timeframe was changing to 20/4, that's why I mentioned it. I'm sure there are a lot of factors, I'm thinking I'm just on a lucky streak, I'll take it though

mmmmbrownies said:

I have +95% success with jiffy peat pucks

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I'm calling BS on 95% females with regular seeds.

Sex is dictated by genetics, period. Science has stated that pretty unequivocally.

There are ways to control the sex via reversals and other such techniques after a plant has initially been sexed, but you cannot control the sex of a run of plants from seed.

GroErr said:

Probably just luck of the draw, I've heard/read about the environment (temps/humidity) potentially controlling sex, but I've never seen a proper study/paper stating it, nor anything related to shorter light periods, just internet talk.

That said, ever since switching my seedlings/clones from 24/0 to 20/4 light cycle I've popped 9 of 10 females from regular seeds. And they ARE regular seeds, 8 of the 10 are my DIY's and I didn't feminize them. Hmmm..... don't want to start yet another internet theory DISCLAIMER: JUST A THOUGHT: some dark period = increased fems? Would love to find some science/data on this.... The 10th is still not sexed, could be fem too, a late bloomer that I haven't been able to read 100% yet.

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maybe ur right, 24/ hrs of light gets u more males wile adding even a few hrs of dark produces more females..im truly starting to believe the enviroment and light period determin sex,,not the seed being geneticlly predetermined..just as with many reptile eggs, enviroment determines male to female ratio...???

13/20 females isn't very convincing. Keep logging your m/f ratio and you'll see over time that it converges on 0.5 ...or maybe it wont! However, without keeping records there is no way for you to say one way or the other.

wait a sec, having trouble parsing your first post:

> the 10 that had 24/0 light sced got 5 males and 4 females and 1 herm.
> 18/6 light sced i ended up w/ 7 females and 3 males
> last run i got 6 females and 4 males under 24/0
> 8 females and 2 males under 18/6

1 - 4f - 5m
2 - 7f - 3m
3 - 6f - 4m
4 - 8f - 2m


So 25 females out of 39 plants, that is 64% female. Easily due to chance and the ratio will drop as you pop more seeds and add them to the list.

Observe & Report said:

wait a sec, having trouble parsing your first post:

> the 10 that had 24/0 light sced got 5 males and 4 females and 1 herm.
> 18/6 light sced i ended up w/ 7 females and 3 males
> last run i got 6 females and 4 males under 24/0
> 8 females and 2 males under 18/6

1 - 4f - 5m
2 - 7f - 3m
3 - 6f - 4m
4 - 8f - 2m


So 25 females out of 39 plants, that is 64% female. Easily due to chance and the ratio will drop as you pop more seeds and add them to the list.

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so ur saying the more seeds i pop the more male average will rise?? so u say if i plant 100 no matter the light or enviroment im bound to end up at a 50/50 rate??

GroErr said:

Probably just luck of the draw, I've heard/read about the environment (temps/humidity) potentially controlling sex, but I've never seen a proper study/paper stating it, nor anything related to shorter light periods, just internet talk.

That said, ever since switching my seedlings/clones from 24/0 to 20/4 light cycle I've popped 9 of 10 females from regular seeds. And they ARE regular seeds, 8 of the 10 are my DIY's and I didn't feminize them. Hmmm..... don't want to start yet another internet theory DISCLAIMER: JUST A THOUGHT: some dark period = increased fems? Would love to find some science/data on this.... The 10th is still not sexed, could be fem too, a late bloomer that I haven't been able to read 100% yet.

Click to expand...

is ther anyway to prove or disprove this theory?? even planting 1,000 seeds under each light sced w/ same enviroment male to female ratio means nothing as there is no proof..even scientists can not prove the seed itself is predetermined its sex, so the theory of enviroment may be true?? yet it is proven that enviroment determines the sex of many reptile eggs...

TheChemist77 said:

so ur saying the more seeds i pop the more male average will rise?? so u say if i plant 100 no matter the light or enviroment im bound to end up at a 50/50 rate??

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Yes, the more you pop the more it will converge on 50-50. Or maybe not? The only way to know is to pop a lot of seeds and carefully log the sex of every single one. It doesn't matter if you pop ten seeds and all ten come out female. I can flip a coin over and over again and sooner or later I'll get ten heads in a row but when I consider every flip I have done then the ratio will be very close to 50-50%.


The only thing that is certain is people that say they get 80, 90, 95% females and don't have data to back it up are full of shit.

TheChemist77 said:

is ther anyway to prove or disprove this theory?? even planting 1,000 seeds under each light sced w/ same enviroment male to female ratio means nothing as there is no proof..even scientists can not prove the seed itself is predetermined its sex, so the theory of enviroment may be true??

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If you pop 1,000 seeds under controlled conditions and carefully keep all the data then you are a scientist and you should write a paper and publish it no matter what the results are.

Maybe environment does have an impact on the sexual expression of cannabis. There are some results that suggest it might have some impact but nothing conclusive. The thing is that the people claiming that environment certainly does make a difference and they are personally getting f:m ratios of 0.8 or 0.9 or higher have nothing to back it up other than their memory and their word, which is worthless.

Observe & Report said:

Yes, the more you pop the more it will converge on 50-50. Or maybe not? The only way to know is to pop a lot of seeds and carefully log the sex of every single one. It doesn't matter if you pop ten seeds and all ten come out female. I can flip a coin over and over again and sooner or later I'll get ten heads in a row but when I consider every flip I have done then the ratio will be very close to 50-50%.


The only thing that is certain is people that say they get 80, 90, 95% females and don't have data to back it up are full of shit.

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Agreed, over the long run, everything must be logged, however will the outcome ever be proof? i would guess that over the years ive gotten more females than males, but this was just a recent test im conducting, as i pop more seeds ill keep track. but dont know if it will ever prove anything either way,,,maybe im better off just going with 18/6 from now on as in the last 2 it won??? i may have a couple hundred seeds but it would take a lifetime to pop them all, especially when im just looking for the best female..i just wonder if there is any proof to this theory and if not who started it and why?? i do agree 90-95% success must be pure luck,,i even had a feminized seed that hermed,,,but never seeen a guarenteed male seed,,only feminized?

TheChemist77 said:

so ur saying the more seeds i pop the more male average will rise?? so u say if i plant 100 no matter the light or enviroment im bound to end up at a 50/50 rate??

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100 is still not enough to guarantee 50/50 but yes that's how it works.

Flip a coin 10 times, and do that 10 times, and if it's not obvious by then do that all 10 more times.

TheChemist77 said:

Agreed, over the long run, everything must be logged, however will the outcome ever be proof?

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No, it is impossible to prove a null hypothesis, e.g. "environment has no effect on expressed gender of Cannabis." It is always possible that some combination of environmental conditions that hasn't been discovered yet causes 100% or even just increased female expression. However, once many experiments with many different conditions are run and the evidence piles up in support of the null hypothesis then that will become the consensus. However, it is always possible that someone could discover a combination of environmental conditions that reliably produces females.

It's just like human hearing. After a century of measuring human hearing the consensus that the upper limit of pitch is around 20,000 Hz for exceptional individuals and that the limit for individuals drops as they age and are exposed to loud sounds. It isn't possible to prove that nobody can hear 30,0000 Hz like a dog, it's just that nobody with this ability has ever been found. Maybe they are out there and have never had their hearing tested but by now this is considered to be extremely unlikely.

Anything's possible but so many variables to come to a definite conclusion. I'll go with luck of the draw or the 11:11 factor, I've been seeing it constantly ever since I started getting all these females. At first I thought it meant that my time was up, but now I know it's a good seed omen - lmao

Ask anyone you know if crime increased and the world has gotten less safe since they were kids and they will almost certainly agree. Things just aren't the same these days. Crime has been getting worse, more shootings in schools and everywhere else, rapes, you name it, they've "been seeing it constantly ever since" they started paying attention. The reality is that crime is back to Leave It To Beaver era levels. Crime in the USA peaked in the 70-80's and has been dropping steadily in every category ever since. Without hard data we would never know it. Even with it, people are afraid to leave their kids out of their sight and people are forced go through legal proceedings to determine if they are suitable parents for letting their 10 year old kids walk home from the park.

Human perception and memory is highly fallable, you'll just have to get used to it.

Observe & Report said:

Ask anyone you know if crime increased and the world has gotten less safe since they were kids and they will almost certainly agree. Things just aren't the same these days. Crime has been getting worse, more shootings in schools and everywhere else, rapes, you name it, they've "been seeing it constantly ever since" they started paying attention. The reality is that crime is back to Leave It To Beaver era levels. Crime in the USA peaked in the 70-80's and has been dropping steadily in every category ever since. Without hard data we would never know it. Even with it, people are afraid to leave their kids out of their sight and people are forced go through legal proceedings to determine if they are suitable parents for letting their 10 year old kids walk home from the park.

Human perception and memory is highly fallable, you'll just have to get used to it.

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One thing I'm sure of, I like how you think.

I'm running an ongoing series of experiments not for popping seeds, but rather for maximizing yields with fewer inputs. This too requires carefully controlled conditions, repeatable experiments and careful documentation. A hunch is a great starting point- and a good experiment is one built to put it to the rest.

I trust my intuition to tell me what direction to investigate. Then, I build the experiment to make or beak it. I've been surprised both by how often my intuition has been wrong- and by how much better my intuition has gotten as a result of testing it over and over again.

I ran a small experiment to see if the environment had any influence on gender.,,,the results are not definitive but interesting

.the 3 plants in the "female friendly" room produced 2 females and 1 male... but in the "male friendly" environment all 3 became female.

IMHO....I believe gender is mostly pre-determined, and the environment has minimal influence but possibly in certain circumstances it could alter the gender

The female friendly room (ideal environment conditions for a female)

• approx 77 F and 70% RH.
• 16/8 light cycle
• 6500K CFL bulbs (blue light)
• General Hydroponics MaxiGro (10-5-14)

The male friendly room (non-ideal environment conditions for a female)

• approx 85 F and 30% RH.
• 20/4 light cycle
• 2700K CFL bulbs (red light)
• General Hydroponics MaxiBloom (5-15-14)

link to the experiment
https://www.rollitup.org/t/can-the-environment-influence-the-gender.846902/