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Flowering with a 18/12 light cycle?

Hm good question. I know they need the twelve hours of uninterrupted darkness, but the 18 hours of light seems extreme. I'm going to make a logical deduction that that may confuse the plants. Just my $.02
 
I don't think it will work. The whole idea of 12/12 is to make it seam like winter to the plant. The only way a plant can tell is winter is because from lack of day light. If you make it 18 hours of lights on the plant will either reveg. or never start flowering. My $.02
 
I think it would but I realize now that I got a lil higher and thought on it. You get your flowers from your veg cycle. So unless I am flowering from sprout Dout there is any benefit.
 
I would never have thought up that question, but it is interesting. My understanding of flowering requirements is 12, uninterrupted hours of complete darkness. Now, is it explained that way because it needs 12 hours of dark, or does it need at least one half of the hours in this new 30 hour day?? How do it know??
 
The length of light is not a factor. More interesting is that regardless of your light/dark cycle or number off hours in your plants day you can flash the plants with red light before12 hours and prevent flowering. Photoperiodism is controlled by pigment response too light immediately following dark. If the plant was dark for 12 hours you get a different behavior than if you flashed it before the12 hours were finished. Simple right?
 
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SSD, your post above does not make sense to me in regard to OP's question. Unless I'm wrong, he wants his plants to flower. I think the 18 hours of light will prevent that from happening. Just my 2 cents.
 
Yes! I knew a grower who tried 18/12 and it worked for him (at least for 4 plants over two grows - I lost contact after that). So I'm pretty confident it works at least for some plants. He said his biggest problem was finding a timer that would do it :)

From what I understand, the plant pays attention to dark periods when it comes to deciding when to flower. The way it can "tell" if it's time to flower is once it's dark it has a certain protein that starts building up in the plant. When the plant is exposed to light (specifically red light), it instantly stops the protein-building. If the protein gets time to build up long enough overnight (an amount of time that is different for every plant, but 12 hours is enough for most strains), that produces a signal to the plant to start flowering. Getting this signal repeatedly causes buds to start forming. So the main thing that prevents flowering is short, interrupted night periods, since that protein doesn't get time to build up enough to make the flowering signal.

However, it wouldn't surprise me if some strains are more likely to run into problems on non-24-hour-based schedules, especially ones that are easily light stressed or have a hard time being kicked into flowering like pure Sativas. But then you almost wonder if a longer night period would help them with that, like an 18/13 (light/dark) schedule or even 19/14... But I'm certain there's a point where adding more light hours will just prevent it from flowering at all.

That being said, personally it seems like an inconvenience since the plants won't be getting up and going to sleep on the same schedule every day (making it harder to schedule gardening time around work hours)!
 
Thanks for the input Nebula, especially since you know of someone that did it successfully. But like you said, some strains would be more susceptible to failure with that schedule and unless you really do your research on your strain, it could prove a failure.

Like I said in an earlier post, if he really wants to know, then he should experiment.
 
Maybe the vegetative/flowering change is based on a ratio, like 1:1 = flower, and anything greater like 2:1 will, just a thought.? Try the different light schedule and if you get flowers, great!, I, myself, would not want to waste my limited grow area on experimentation, but "to each His own".
 
The thing that builds up in the plant is known as "Florigen" though we still don't understand its exact nature. I recently found an interesting study where they found they could use a response regulator known as "EMF1c" to affect Florigen levels separate from the light period. Who knows what could be available to us in the future? Now is an exciting time to live in the growing world :)
 
Sounds like a perfect experiment for Greenie! Get on it!

I have heard of success with 15/12. 18/12 is a new one to me. I suppose if you have stable genetics and can actually find a crazy timer like that, then go for it! Just let me know how it turns out :)
 
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