starting seeds under 12/12 with intention to veg

mad librettist · Jan 12, 2012

Heya gang, I have a botany question.

I am experimenting with starting seeds under 12/12 with the intention of increasing day length thereafter and veging for some time under 18/6.

How long can I have a seedling under 12/12 without triggering flowering?

dizzlekush · Jan 12, 2012

In a Cervantes book he suggests 14/10 until the first pair of non cotyledon leaves are developed to increase the amount of seeds that develop female. He claims that he got this advice from a seed breeder. Cant remember which one

Im fairly certain Ethephon, 6-BAP or possibly even negative temperature differentiation for dark periods would be just as likely to increase female %. I can cite literature if this is the goal of your experiment.

VerdantGreen · Jan 12, 2012

mad, i've done a similar thing and if you go back to 18/6 or whatever as soon as they show sex then they seem to carry on vegging just fine. if you kept them on 12/12 for much longer than that then you would probably get into a revegging situation and the associated growth check.

Duplicate · Jan 12, 2012

Interesting idea! (tagged)

Chimera · Jan 13, 2012

dizzlekush said:
In a Cervantes book he suggests 14/10 until the first pair of non cotyledon leaves are developed to increase the amount of seeds that develop female. He claims that he got this advice from a breeder, 'Chimera' from Chimera Seeds if memory serves. No idea if any relation to Chimera, the member here on IC

Im fairly certain Ethephon, 6-BAP or possibly even negative temperature differentiation for dark periods would be just as likely to increase female %. I can cite literature if this is the goal of your experiment.

>> I didn't give that advice to Jorge. I am however editing and co-authoring the newest book and that piece of info will not make the next edition, fwiw.

Gender is determined at fertilization... you can alter the sexual expression of a seed's gender via applications of ethephon (or sts) etc but the effect transient on only temporary.

-Chimera

motaloca · Jan 13, 2012

i am at n13 lat, so i have 12 12 minus, plus 1, 2 hours all year round.i start outside and put them under 18/6 when they show sex(depends on strain but generally around 20 days from breaking soil). so far i haven't had any problems(if i put them under 18/6 at first sign of sex).

I found when i put them back under 12 12 they will start flowering faster, than plants who spent all their lives under 18/6.

Tom Hill · Jan 13, 2012

Starting seed under 12/12 is fine providing as others have stated one moves to a longer lighting duration at first sign of visual sexual differentiation (assuming one doesn't want them to flower). Sex will be more pronounced under this duration, eg, instead of only primordia at the 3rd, 5th, or 7th node, we'll likely see fully developed pistils. Plants will have a greater internodal length under this regimen as well, and branches will be less developed than those of a longer lighting duration. -T

mad librettist · Jan 14, 2012

Thanks guys, very informative.

My goals are as follows:

Maintaining fertility by keeping plants in there at all times
shortening the time required in my veg tent
make use of empty spots in the flower tent (perpetual)

My veg space is only half as big as my flower space, so if I can make use of all spots at all times that is reducing the bottle neck.

Ground Up · Jan 14, 2012

Hey chimera , ... You have been around the genetic BUSH for awhile .!!! What would say is best genetic?strain structure for indoor and outdoor!! By the way love your work............... no homo !! LOL

supermanlives · Jan 14, 2012

VerdantGreen said:
mad, i've done a similar thing and if you go back to 18/6 or whatever as soon as they show sex then they seem to carry on vegging just fine. if you kept them on 12/12 for much longer than that then you would probably get into a revegging situation and the associated growth check.

wow i am gonna try it on some extra seeds. c4 sucked. aurora was fine along with everything else. tom and chimera you guys rock . keep up the good work . stay safe guys. you are a constant source of valuable information and genetics. big props for all you do

Phaeton · Feb 28, 2012

This all sounds suspiciously like the 12/1 clone/veg I use, but I don't have to swap to 18/6 as the plant will not go to full flower.
Yes, the buds show up days sooner when put to 12/12, with less stretch involved. Internode spacing is controlled by spectrum and intensity during the veg cycle.
All in all, when set up correctly it is win win win with shorter light periods.
"correctly" is proven to vary quite a bit, I cannot grow both sativa and indica correctly in the same room. Requirements are not close enough. I chose sativa, yum yum.

trichrider · Feb 28, 2012

ummm, how long before they show sex the way you used to do it?

that long.

i know where you're going with this and i concur it seems more natural.
did the very same thing this turn.

de145 · Feb 29, 2012

Chimera said:
>>
Gender is determined at fertilization
-Chimera

Wow! This is huge news because there are a zillion theories out there and this is the first I've heard that they are all wrong but if this is true it makes my life a lot easier.

Can you confirm how solid this information is?

softyellowlight · Feb 29, 2012

de145 said:
Wow! This is huge news because there are a zillion theories out there and this is the first I've heard that they are all wrong but if this is true it makes my life a lot easier.

Can you confirm how solid this information is?

Whaaaaaaaat? We've always known that the chromosomes determine the sex. The sexual expression, however, is more than just a genotype, and pistillate or staminate versions of a plant of the opposite chromosomes can appear. If you look a little bit, there was a recent thread about "males" in feminized seed populations. The current best theory is they're actually... "butch females!"

sgapetti · Mar 1, 2012

great info mad, thx for sharing, i am testing rigth now to see how it works , perfect for my micro cab :wave:

de145 · Mar 1, 2012

softyellowlight said:
Whaaaaaaaat? We've always known that the chromosomes determine the sex. The sexual expression, however, is more than just a genotype, and pistillate or staminate versions of a plant of the opposite chromosomes can appear. If you look a little bit, there was a recent thread about "males" in feminized seed populations. The current best theory is they're actually... "butch females!"

Oh, now I'm confused. I've always been under the impression that the environment can affect the percentage of males to females you get from a given batch of seeds.

Your earlier post led me to believe this is not the case and the sex is pre-determined in each seed and nothing in the environment can affect that except temporarily in certain cases.

So in other words it appeared to me that I could now not worry any more about the zillion little environmental things I have collected in my brain that could affect sex like too few nutes for seedlings or too much or wrong temps or wrong lighting or what have you.

I'm getting hung up on your terminology I think.

Leaving aside special unusual cases where a plant can be forced to express different sex organs, are you saying that the sex of a plant is pre-determined and nothing ordinary in an environment is going to permanently change that for seedlings?

softyellowlight · Mar 2, 2012

The sexual expression is mostly pre-determined -- you can affect it acutely with hormones and cause complete "reversal" or partially with environment and possibly cause one expression to be more likely than the other, assuming the genetics also rolled that way. Here's the thread I was referring to:
https://www.icmag.com/ic/showthread.php?t=231950

sgapetti · Mar 15, 2012

After reading this 3d i switched 2 seedling on 12/12 from seed back to 24/0 after sexing,

the left one is 3 day ahead of the right one that have been sexed by preflowers

3 days ago, after six days, the left one is still stretching, while the right one , sexed by preflowers is still growing.

today, after 9 days, left one still flowering, stopped stretching? , while the right one , sexed by preflowers is still growing.

Peace S

Eol · Mar 29, 2012

Really interesting thread! Have been following sgapetti's grow so I'm very interested to see how his 12/12 from seed experiment progresses.

If this works well it will make life so much easier for scrogging micro growers. In my last grow, I had to wait for preflowers to show, but by that point my one female was too big to successfully weave into the scrog screen, so I had to take clones and start pretty much over - pretty annoying! This technique would have saved me so much time!

I was also thinking, I've always heard that a plant's roots grow predominately at night so by giving the seedling 12 hours of darkness to start off with are you creating a bigger root mass for when you do switch to veg?

Cheers, hope this thread continues to develop - I will be definitely trying this on my next seed run!

Eol · Apr 14, 2012

could you give us an update on their progress sgapetti? :prettyplease:

starting seeds under 12/12 with intention to veg

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