more than 12 hours light for flowering

[l orange bud l]

just wondering if anyone has been able to flower with more than 12 hours light. maybe using more than 24 hours in on cycle. so like 12 hours dark and 13 light. is there any reason to stay within the 24 hour cycle? i was thinking as long as there`s 12 dark, then that should be enough.

i have vegged on 13 hours light, had the light comming on half way through the dark period for an hour and that kept em vegging. but if i changed it to a 25 hour day, with twelve dark, 13 light then maybe they could of flowered.

heres a link to some complicated shit that i couldnt understand. maybe u guys could make some sence of it.

http://cannabis.com/growing/lighting...er_yields.html

cheers

 

[ssq.talker]

u can put them on 14/10 withno problem but it depends on strain u growing some strains need more night period.

 

[trichrider]

11 on, 13 off.
saves electric, makes cents.

 

[l orange bud l]

i would like to hear if anyone has tried 30 hour cycles or 40. not staing in the 24 hr

 

[f-e]

5 years on, I find this thread title might offer another use.

I have an indoor/outdoor strain, that is weeks into flower at the 14 hours of daylight point. It doesn't actually reach 12/12 here until the 25th of September, When it's possible to chop it down.

Lets say I were to flower that indoors, with 13 hours light. A day length when it's fully stacked up outdoors. So I know it's most certainly in flower with no hint of vegetative behaviour. If using the same lighting, I could put in more energy per day, what would happen? Would I simply get more plant, or would the plant finish sooner, having had a number of hours in flower, not a number of days.

That might be worth going over. If a plants wants 12 hours, for 50 days, that is 600 hours. Is the 50 days, or the 600 hours the important bit.

I did once put unknown indoor plants through some testing, but it was amateur hour stuff. I found that at 14 hours, some started showing the veg signs of elongation. Others seemed to be in limo, like thay kept flowering, but might of never got old. A couple of runs we extended he days after the first two weeks of 12/12 and kept them going. Going past the usual finishing date. Then we shortened the days below 12/12 to finish them. I think this was related to the fact they were not pressed into finishing. It's so long ago now that my findings with them unknown plants has limited value.

So, my indoors/outdoor I know to be totally into flower at 13 hours light. What would it do beside another at 12/12 ??

Anybody done such a side by side?

 

[Hookahhead]

I have flowered plants indoor under 13 on 11 off. In my opinion what really matters is the Daily Light Integral (DLI).

The Daily Light Integral (DLI) was developed by scientists to provide a measure of cumulative photosynthetically active radiation (PAR) received by plants over the course of the day. It integrates light intensity in micro-mols per square meter per second (μmol/sq m-sec) and totals this over a 24-hour period. The total daily integral is expressed as mols per square meter per day (mols/sq m–day). The concept is similar to totaling daily rainfall measured in inches per day.

https://www.greenhousemag.com/article/gm0915-photosynthesis-plant-light-dli/

What this basically says is your plants ideally want X amount of photons per day for optimal growth. So you can run higher intensity light for shorter duration, or lower intensity light for longer durations.

If you set up a time lapse for a week, you will hopefully notice that there is a certain point where the plants start to droop and “go to sleep” before lights off. This indicates that plants have met their DLI and any further light doesn’t provide much benefit.

Of course we still have to worry about photoperiod sensitivity in cannabis. Research shows providing far red at the end of a light cycle helps a plant transition into “night mode” quicker, allowing the photoperiod sensing hormones to build up faster. This is one reason some plants may flower under 14 hours outdoor, but need 11 or 12 to flower indoor (without supplemental far red at the lights off transition).

Using these two ideas (DLI and Photoperiod sensing hormones), you can choose what works best for your lighting setup. If you have a really powerful LED, you might only need 11 hours. However, it may be more economic to run slightly less watts for longer duration. Just one more caveat to dialing in YOUR system.

 

[f-e]

That was very interesting. The bit about them sleeping when they have had enough, rather than at a certain time of day, was particularly illuminating. I saw this particularly early with lm301 leds at 30w per foot. Just 14 hours of the 20/4 saw half of them having a nod.

 

[Hookahhead]

Awesome, I’m glad you’ve seen this first hand f-e. In the situation you described (drooping at 14 hr), you would probably benefit from running lights on for 14, off for 4.5, on for 1, off for 4.5, repeat. Basically just breaking up the 10 hour darkness with an hour of light in the middle.

Even though you’re cutting 5 hours of light every day, I would hypothesize that you’ll see equal or better gains. Giving the plants that little nap would allow them enough time to “reset”, so the hour in between is actually being utilized effectively again.

Of course this is easier to dial in with a mono crop as each plants DLI will be slightly different.

 

[f-e]

It could of really helped actually. That particular grow was a nightmare. If I lowered the lux level, they didn't drink. So I had to put in a lot of food, to last till the next fertigation. Too much in fact, and it didn't last. So I swung from over feeding to under feeding, every time. Raising the lux level, along with the little radiant heat that provided, Just gave new problems. I'm wondering if that was high feed, when they were trying to sleep with the lights on. It's all history now, and a bad chapter at that. They did pull around the moment they went into flower though. Which is a key indicator that they wanted a decent rest. Watching them sleep before lights out is normal, but switching to leds and seeing it so early in the day... at maybe 30,000 lux.

There is a paper making the rounds, about using far red to set the 24 hour rythem. I have no interest in getting them to sleep quicker as I have lots of spare hours in my 24. But I'm looking again if they are short day or long night plants, and just how we might move from 24 using such a technique. Not all plants in nature even care about the circadian rhythm, just as long as the light or dark is right.

It's a subject often visited, but I don't see trialed

 

[Hookahhead]

They are long night plants. I forget the name of the actual flowering hormone at the moment. Anyhow, it’s concentration increases during lights off, and is reduced quickly when the lights turned on. Increasing the nighttime hours increases the concentration of this hormone. There is a certain threshold, that when this concentration reaches a certain level for several successive nights the plant will trigger to flower.

 

[f-e]

Photochrome isn't it? Or was that an effect from some image manipulation software. PFR and all that. I have a friend who even had the timers made, but never did I see anyone stray from 24 hours days, and come back to tell the tale.

 

[f-e]

I have the results from tests done on a different plant. The article thinks short day is long night, so is of little use. But the results are from a different unknown source. Half way down the page, looking like a horizontal bar graph https://www.hammiverse.com/lectures/39/1.html

It shows a plant getting 16 hours light each day, with the night starting at 5 hours. A 21 hour day. The plant in question wanted 8 hours sleep or more day to flower. Which we can also view as a 24 hour day, or more.

They then moved on to changing the day length. 7 9 or 12 hours. The plant then wanted 9 hours dark in each case to flower. So at the extreme end of that, 7 on and 9 off making a 16 hour day.

The internet obviously has a lot of information to wade through. A plants rhythm seems to be more tied to nights than days though. However, we see lots of testing done with single plants, such as the flower used above. There is no reason to expect our plants to do the same though. Or even for all our plants to do the same as one-another.

It looks to me like the plant above was happy with a 8 hours sleep when working around a 24 hour day. But once they moved away from 24 hours, a longer sleep was needed, to prioritise the response to nighttime higher than the 24 hour rhythm.

I believe I have seen some signs that align with that. Say I keep a mum, then the cuttings, and the veg period, all done under 24 hours light. I see them all nodding off at different times of day. Any time of day. They loose track, but I haven't watched them as much as I would like. That is a study on it's own. I have watched what happens when they go 12/12 though. It might be wishful thinking, but I find a long sleep on the first night will get them all on the same timeline. While just going 12/12 leaves some taking longer than others to find that rhythm. Basically needing a little more persuasion to adopt the new timeline.

In the past, there has been talk about lengthening the day beyond 12 hours, but keeping the 12 hour night. I think we could exhaust a plant in under 12 hours light though. Keep the 12 hours night. Getting more days in a week.

 

[troutman]

The more hours of light the longer it takes to flower assuming you have something that isn't a pure Tropical plant
that will stay in vegetative state for a very long time. My outdoor plants start to flower in July when there's over
15 hours of light. But indoors under 12/12 the same plants finish faster.

 

[TychoMonolyth]

I read on here that someone with ages of experience was growing 12/1. The one hour of a simple 100 watt bulb in the middle of darkness was enough to keep it in veg. Saves huge amounts of electricity.

I personally think it's the gradual increase of darkness that triggers flowering in most strains. And I mean consistently GRADUAL. Like 2.5 minutes a day. But that's outdoor and what do I know. Still, this would allow for flowering to start at 15hrs of light.

 

[Hookahhead]

In the past, there has been talk about lengthening the day beyond 12 hours, but keeping the 12 hour night. I think we could exhaust a plant in under 12 hours light though. Keep the 12 hours night. Getting more days in a week.

Dude you just blew my mind. I kept thinking about methods to increase the daylight to 14-15 hours to give the plants extra time under the light each day.

However you’re absolutely right, you can accomplish the same thing by just “shorting” the days. For example, if using powerful LEDs, we may discover our DLI is 10 hours. So putting a plant under a 10/12 schedule frees up 2 hours each day. Over the course of a week, we gain 14 hours. This gives us a little over 2.5 extra days per month. Bonus points if you can get the plants to accept a 10/10 schedule, freeing up 28 hours every week. You all know the song... “Ain’t got nothing but love girl... 8 1/4 days a week!”

https://m.youtube.com/watch?v=kle2xHhRHg4

 

[f-e]

At 12/12 under leds I have seen some plants closing up for the last few hours, to limit light exposure. Not sleeping, but surely they have had enough. I don't think it's much over 40,000 lux, and will look into it further.

 

[zif]

I'm really enjoying seeing you guys take this somewhere totally unexpected!

A side thought - if the cheap timers were not 24hr cycle timers, but arbitrary on/off period timers, we'd probably know a whole heck of a lot more about this by now.

 

[Dankwolf]

If I havr a mainly indica run I adjust the hours to 13 on 11 off helps with yield , stretch and defoilating issues . especially if your hero or dwc

 

[AgentPothead]

I read on here that someone with ages of experience was growing 12/1. The one hour of a simple 100 watt bulb in the middle of darkness was enough to keep it in veg. Saves huge amounts of electricity.

I personally think it's the gradual increase of darkness that triggers flowering in most strains. And I mean consistently GRADUAL. Like 2.5 minutes a day. But that's outdoor and what do I know. Still, this would allow for flowering to start at 15hrs of light.

Every time I look I can never find the citation again, but I swear I read somewhere that it only takes 6 or 12 minutes of light to reset a plant back to daylight mode.

 

[TychoMonolyth]

That would suck.