Change 12/12 back to 18/6


So i have a jack herer auto it was 35 days old and no pistils. I decide it to change 12/12 to show the pistils. After changed the light it showed about 3 days, and she is flowering.

Can j change the light back to 18/6 or she will be hermie ?

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I’d love to know the answer to this as well (relating to switching back for autos)! @dbrn32 ?

This Goldleaf has been in veg for almost 14 weeks, so it was suggest I switch to 12/12 from 18/6 to induce some flowering (which it did).

Well, these are the new autos zkittlez and gelato that are also in the tent and actually started showing pistils pretty early on (before the switch). I’m moving from a 2x4 to a 4x4 tent soon. Would switching back to 18/6 give the little ones more time to veg but keep the Goldleaf growing strong? Will that re-veg as well?

If you had to move to 12/12 to get it to flower, then I would leave at 12/12 for the duration. Some are probably stable enough that you could move back to longer schedule, but I would bet not all. Imo not worth risking plant herm or reveg.


Thanks @dbrn32 ! Does that mean the other 3 will be stunted?

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I guess depends on your definition of stunted? They are autos correct? They look fine, just small. If you have good enough light density you can hit recommended dli on 12 hour schedule, so length of light time isn’t critical from that perspective. They are flowering, so growth in terms of plant size is pretty much over. I would say this is inherent risk that is pretty much accepted when choosing to grow autos. To get large plants you typically need a system that produces rapid vegetative growth or hope they are like your gold leaf and don’t want to flower easily on the long schedule.

If you are simply wanting to ensure you have larger plants, try photos next time. That allows you to control veg time, and essentially get plants to the size you want them prior to flowering.


That’s s bummer because my first autos were MUCH bigger and I’ve seen far larger auto grows on forums. Thanks for the info - lesson learned!

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For sure. There are members here that grow them pretty big, but most are in soilless media utilizing high frequency feeding methods or some sort of passive hydroponic system like an autopot. All known to provide fairly rapid growth when compared to soil grow. Sometimes experience can help a bunch too, and others plants just flower early.


Hello! Just hoping to get a little more info on this thread. I’m very new so apologies if I’m using the forum incorrectly. dbrn32, you already advised on this topic, but can you comment further on genetics quality and how it affects the risk of stress leading to hermaphrodites? Also wondering how yield would theoretically be affected with an auto if someone did 18/6 or 20/4 all the way through to harvest vs. 18/6 and switching to 12/12 during flower (I did not research appropriately and am in a live and learn situation lol, having a great time with the hobby though so its all positive! This community is great too.)

I have 1 healthy, topped, scrogged GG4 auto in a 32"x32" tent. Fills the tent, flat canopy numerous bud sites. Under a mars hydro ts 600 and a feir electric 86 watt. Started germination 5.9.2022. 18/6 light from start. Currently at approx week 8.

About 3 weeks ago I saw first preflowers (I think). About a week ago, when I noticed many pistils flooding in, I switched from an 18/6 to 12/12- I am new and hadn’t done adequate research on differences between photos, autos, etc. Based on my research, I now understand that generally accepted for autos is 18-24 hours light all the way to harvest. I believe I should have kept the same schedule, but you live and learn.

I switch back to 18/6 at this point, after a week at 12/12, do I run the risk of stress leading to a hermaphrodite. Is switching back even worth the risk i.e. would yield potentially be much different if I switched back vs. keeping 12/12? The internet is very split, many places say the switch would have no downsides and allow the plant more energy to do it’s thing. Others say they wouldn’t dream of making that switch due to stress, stunting, stretching, hermaphrodites, and various other reasons.

Do you have any thoughts on what you might do in this situation, besides educating oneself and not making the mistake in the first place (I know you already said to stay with 12/12, but can you comment further on when/if you would switch back to 18/6 in this hypothetical situation? Thanks in advance if you have any thoughts.

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[quote=“mkglue, post:8, topic:59337”]
can you comment further on genetics quality and how it affects the risk of stress leading to hermaphrodites?

This basically just the breeder taking time to grow their stock amd see how it does. Some people do amd others don’t. But someone wanting to maintain a good reputation would test their seeds before releasing. That being said, you could probably make anything hermaphrodite if pushed hard enough.

Could be very little or a lot. All comes down to light intensity for amount of time. If ppd average is double for 12 hours as opposed to half for 24 hours mols per day equal. So the theoretical harbest potential would be equal.

Your light is small for the space. If your auto will flower on 18 or 20 hours of light time i would probably stick with this or get a larger more capable light and flower on 12 hours.


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