How about an 18/12 light cycle?

Best way to up the yield with your photoperiod plants... ....have them grow in the SUN. Period...unless u got an idea to top that orb in the sky...yup- peeps should stop trying for outdoor yields while growing in a closet...

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I don't have the benefit of growing outside anymore, I just moved to a house in the city at the beginning of the year and started growing hydro.

It's basically manipulating the circadian rhythm... It's assumed that since Earth has 24-hour days, all plants and animals are entrained to it. But in my opinion, not every plant or animal is created equal... 24 hours is just the average norm. Some things might do best with longer or shorter days...

I do always find it funny how on this forum if you come up with a idea ppl are willing to bash it for no other reason than they are not doing it the normal way, I like outside the box thinking........after getting flamed down in the forum a while back about defoliation I tried it and got a got increase in yield.

Shippy there is no reason why as you said you couldn't use a digital timer and try this. The thing that would get confusing is if your flower time is ten weeks, would it actually take longer because 10wks is 672 hrs which would be 336 hrs light and 336 hrs dark but you wouldn't be achieving this as you would deduct 6 hrs of light from the dark every 30hrs???? Make sense

Shippey123 said:

And thanks I will.

Click to expand...

To me it would seem to be a waste of a grow cycle to test something that would have been done already by now, by someone, somewhere. I would simply focus on genetics and nutrition. I can tell you one thing that I have tested, that is the 18-24 hour darkness period for the last few day's of bloom is in my opinion is a total line of shit, unless you are growing schrooms. Then it works. Interesting thought though, Shippey123. Peace out

I thought about that to. By extended the day from 24 - 30 hours (take a plant with a 60 flower for example) it is going to add say 10 extra days for that plant to reach its 60 day finish. But if it's going to increase yield and resin production then why not? And also it's not a total waste of a run because what if it works out and I get an extra oz off each plant? Or it don't and I end up with hermies or a small yield? Either way it'll be a good learning experience.

I'm a first time grower so I don't have experience but I can say I have researched for days before my first attempt and I have never seen a thread even mentioning more the a 24/0 schedule. Again complete noob but just stating the obvious. If it was worth mentioning or trying you'd see more post or such a thing

Thats the thing though, I keep seeing people talk about doing it but I haven't found anyone who actually has. In theory this should work out but I can't seem to find any proof of it going either way.

I've also come across this a few times in my search for answers. Does this one make any more sense?

The Theory
The theory behind the 18 hour Day/Night cycle is that during a normal 24 hour light cycle plants will usually achieve high growth rates peaking at 100% capacity during the first 50 - 60% of the day. The growth rates will then diminish rapidly and the last 20 - 30% of the day achieves minimal growth. So by reducing the length of the day we are triggering an increased growth mode where the growth rates are at their peak for the majority of the day. This effectively achieves a very fast growth cycle with full yield potential.

NOTE: To achieve these incredible growth rates it is important to provide maximum light intensities and CO2 enriched conditions. The recommended lighting is 600W per square metre.

The Cycles
Vegetative Cycle - Lights ON 14 hoursLights OFF 4 hoursFlowering Cycle - Lights ON 6 hoursLights OFF 12 hoursThe BenefitsThe growth achieved during an 18 hour cycle can be the equivalent to that achieved during a 24 hour cycle. So by running 18 hour cycles the same growth and yield can be achieved in 75% of the time.
Reduced day lengths also mean reduced power consumption. Grow more and use less power. Who can argue with that?
For example, an average crop grown from seed using a 24 hour day/night cycle will have a 4 weeks grow cycle and an 8 weeks flower cycle. This equates to 28 days @ 18 hours a day and 56 days @ 12 hours a day = 1176 hours of light over 12 weeks.

An accelerated crop using an 18 hour day/night cycle will achieve the same yields using a 3 week grow cycle and a 6 week flower cycle. This equates to 21 days @ 14 hours a day and 42 days @ 6 hours a day = 546 hours of light over 9 weeks resulting in a 40% reduction in power consumption and a 25% reduction in crop time.

It's basically the opposite of what I'm going for here.

Answer from the great mind of Ed Rosenthal

What would happen if I gave my plants a 27 or 30-hour day instead of 24? I would use a seven-day timer to turn the lights on for 15 to 18 hours and then give the plants a 12-hour dark period. Would this lighting make the plant grow faster or have a larger harvest?
Doctor James,
Internet

I think the plants would accept a longer cycle of 27-hour days and continue to flower. The next question is, "Is it worthwhile doing this?"

The idea of long cycling is to increase the percentage of time the plants receive light to increase growth. Under normal flowering conditions plants receive 12 hours of light and 12 hours of darkness each day. If a day were increased from 24 to 27 hours and the plants were lit 15 hours and in darkness 12 hours, they would be lit 55% of the time, an increase of 10%.

Let's say the plants had a 70-day cycle. For plants cycled to 27-hour days, it would take an additional nine days to complete the cycle. The plants under the normal 12-12 cycle would receive a total of 840 hours of light during flowering and the plants under the 27-hour cycle would receive 1,050 hours. Would the extra nine days, almost 13% more time, induce harvests more than 13% more bountiful? I think they would. Also, the buds would grow larger, resulting in higher quality produce.

I must admit that I have not tried this experiment. If altered cycles intrigue you, try it on only a small portion of your crop. Experiment first, before incorporating the plan into your entire program.

Another way of increasing the percentage of time the plants spend under lights is to find their critical forcing period. Outdoor growers may have noticed that some of their plants begin flowering long before September 22, when the day and night length is each 12 hours. Plants that begin to flower in August or early September are obviously triggered by fewer than 12 hours of darkness. Finding a variety's critical day length takes either observation of outdoor growth or some experimentation indoors. If a plant were to flower under a regimen of 13 hours of light and 11 hours darkness, it would be lit 54% of the time and under a 14-10 hour regimen it would be photosynthesizing 58% of the time.

There is also the possibility of finding the plant's critical light period and using longer days. Under the 27-hour regimen, with a critical time factor of 10 hours, the plants would be lit 17 hours of each day, or about 65% of the time.

Did doc James actually do the experiment? Any results or just the verbiage... reads like trying to keep a plant in a perpetual bloom state... very cool in theory-- Loads of variables to call anything definitive I would think, especially with small samplings... but I'd be down to follow when/if you go down that road...

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I'm not sure if he did or not, that was just a question and answer thing Ed does. I tried looking up the guy and 18/12 light cycles but had no luck. I'm not entirely sure what will happen, and I'm not seeing anything that anyone else has posted about there luck with it. This harvest will be done in less than two months, and I don't see it as a problem so I'm gonna probably do a side by side comparison using Jack47s clones. I got a few feminised seeds left I can set a mother up with. And I'm going ro share my results from start to finish here on RUI so that if anyone else happens to ask the same thing there will be a thread on it!

Have you looked for any similar evidence from other species which are day/night length dependant? Sure it wont give a clear answer, but surely in the wider world of production horticulture, there must be usage of alternative light schedules?

Sounds like an interesting experiment for sure. Don't worry about people knocking you back. Despite me agreeing with them about plant evolution being above and beyond human buffoonery, there are still many aspects of nature which are yet to be tested and understood. At the end of the day, the plant is responding to stimuli to trigger metabolic processes, so working with an understanding of them in their natural state leads to all kinds of possible manipulations. Go forth!

That's a real good point about other applications using it, just a question from veg to flower assuming your using 18/6 is it the extra 6 hours dark that activates the flower stage

Why are people always thinking of ways to fuck with simple growing. Not to say growing is simple but there's a tried and true formula foe growing weed indoors.In my opinion what you'd get from this method is a confused plant and be in deep shit if your timer doesn't cooperate. I'm all for quality and quantity when it comes to my grows and the 12/12 formula gives me just that. Weed takes long enough to produce as it is why waste all of that time fucking with the light schedule when if yo're lucky you'd get the same or similar results from the tried and true 12/12..Let me state that I do not consider myself an expert however I've been growing quite successfully for over 3 years and I think the idea sucks..

The Science in Layman’s Terms
Cannabis plants are referred to as long night or short day plants, because they require a long period of darkness to trigger the hormones that tell the plant to switch from vegetative growth to flowering. These light receptors are color pigments in the leaves called Phytochrome Red (PR) and Phytochrome Far Red (PFR). These pigments get their names from the types of light they absorb. PR absorbs red light between 660 and 760 nm and PFR absorbs far red light between 760 and 800 nm. These two pigments chemically react to the light, and trigger the plant to flower or not.

This is where it gets a little confusing.

In cannabis plants, the normal presence of PFRswitches off the flowering signal. The level of PFR is what you can manipulate by adjusting the photoperiod. PFR is quickly produced when plants are exposed to light that contains far red wavelengths. When there is light, the PFR and PR maintain a balance. When the sun goes down or the lights go out, the darkness gradually switches the PFR to PR. Because of this, PR levels gradually increase and the PFRgradually decrease during the dark period. The presence of PR is a neutral condition to the plants and essentially tells them nothing. When the light returns, or if a small amount of far red light interrupts the dark period, the PRimmediately switches back to PFR. If the plant is without light long enough, the PFR will decrease past a tipping point. This decreased level of PFR signals the plants that Fall is approaching; and the plant begins flowering.

In short, the presence of PFR due to long hours of light and short hours of darkness keep the plants in the vegetative phase. If the plant experiences enough hours of darkness, most of the PFR turns to PR ; and the low level of PFRsignals the plant hormones to begin flowering.

I understand your point Bullwinkle, why fuck with something that has been working perfectly for as long as anyone can remember. But I like to think outside the box, and I don't see why the plant should be limited to a 24 hour day just because that's how nature is. We already control everything when growing indoors so why not see if changing the light cycles doesn't make a difference?

Has anyone actually tried the 18 hour day/night cycle (6/12)? I'm curious about it. Might try it out and see what happens.

I found a few post about the 18 hour day while looking for my own answer, saying that most of the plants growth happens within the first 6 hours after lights on. I copied what someone had said on one of them and pasted it on here earlier in this thread. There was a bunch of skepticism like I'm getting here, but they were also saying the harvest were the same as a 24 hour 12/12 cycle.