Having over 12 hours of darkness, should dramatically decrease flowering time. It lowers by around 40% if you drop a few hours of light. The plant thinks winter is getting closer and closer, so tries to finish flowering as quickly as possible to avoid dieing before it has a chance to become pollinated and drop seeds. Note, you will lose a lot of yield, the plant wont be getting anywhere near as much light as it should be. 12/12 is the perfect balance!

Well, you guys are spouting what most growers think is logical.

Sometimes, that is not how it actually works.

Cannabis will be induced to flower, and will continue flowering, if the "critical daylength" is maintained. We know that is actually the hours of darkness that is required. And it's different for different strains of cannabis.

We know that 12 hours of darkness will maintain flowering in all strains, so we give them 12 hours of light. We also know from our reading in Marijuana Botany that giving them less than 12 hours of light will cause less THC to be produced. You can refresh your memory here:

Rob Clarke sez in Marijuana Botany: So that tells me that I want to give my plants as many hours of light in each day while still giving them enough hours of dark to keep them flowering.

HTH

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i think i will stick to 12/12...sometimes I give them 13 hours the last few days..but I dont know if it makes a difference..

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http://www.sachydro.com/**Cali's Sea Of Green/purple**--*CALI'S Bong Rip Thread*--

I found this video on this subject: YouTube - THC Seeds - How To Grow Marijuana (4of4) Weed Cannabis Ganja

Sorry guys and gals. They switched the video on me. Will try to find the correct one.

I went to 14-10 (light/dark) after two weeks of flowering cuz I thought they would be set....but I didn't like what was happening....they were stretchinging the nodes more than I wanted so I went back to 12-12 for like anotehr five weeks....and now with two+ weeks left have gone to 11-13 (light/dark)....for no particular reason, I just wanted to......I like how they are doing now.

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Ride hard, Ride long....git put away Wet each and every time....no holdin' Back.....enjoy the journey ...... cuz that's ALL there is! Walk on and walk tall folks!

stay with the 12 on 12 off , all your gonna do is extend the flowering time it won't increase your yield...just another opinion

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Blackdog

I have not done the experiments myself, but statistically I doubt that the effect would be strong. I would look for other possibilities to increase yield. Besides my plants stick to a schedule and when my one set of plants are sleeping the other set is reaching for the sun!!!

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"Don't blame weed, blame me."-We1

I've know some1 who flowers 13 on / 11 off and he swears by it. If you think about it from start of flowering to harvest approx 8 to 11 weeks depending on strain, 1 more hour every day, x 7 (week) x 10 average flower weeks, that's 70 more hours of light, or more than 3 days of solid light. It makes a difference!

I could see how 13/11 could be either good or bad, someone do the experiment and let me know.

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"Don't blame weed, blame me."-We1

I posted this question a few days ago, but didn't get a response. I'm wondering about my clones: I am (hopefully) approaching harvest time for the moms, and moms and clones are under the same light (400W mostly red HPS) 12/12. I was wondering if it'd be o.k. after harvesting the moms, to change the light back to 18/6, switch to mostly blue MH (400w) for the clones. They've been with the moms under HPS 12/12 for a few weeks now, and I have no idea how long untill harvest. They don't seem to be preflowering or showing sex yet (thank goodness, cuz they're under a foot tall).

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i think i'm using weed as a fill-in, cuz mary always lets me hit it.....