# 24 hours or 18-6?



## blowinthatloud (Oct 25, 2014)

I have always used 24 hour lighting for veg then went straight to 12-12, been reading an some say they grow better with the short dark period any proof?


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## Locked (Oct 25, 2014)

Most of us Veg 24-0. MJ does not need a dark period.


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## Hushpuppy (Oct 26, 2014)

agree


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## Dr. Green Fang (Oct 26, 2014)

Agree


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## Sherrwood (Oct 26, 2014)

In addition if your growing indoors putting them into dark makes them stretch for light, not good for indoor grows. 
24/0 as stated above.


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## Hackerman (Oct 26, 2014)

Can someone explain to me what it is that most plants do at night that cannabis doesn't do?

AKA, why doesn't pot need a night cycle when vegging?


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## Rosebud (Oct 26, 2014)

I think most plants have sex at night and MJ doesn't.

I can not explain scientifically why. But if you do two grows, same variety, and one under 24 hour light and the other on 12/6 or what ever, the plant will show you.  It doesn't stretch under 24 hour light.  I learned quickly when i got here that it is true.


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## Hackerman (Oct 26, 2014)

I don't doubt that it's true, I was wondering WHY. LOL

You remember the little 10 year old kid in the neighborhood (everybody had one) that always kept saying, "Why?" to EVERYTHING?

Well, I grew up and found my way to your forum. LMAO

I did some Google searching on this and didn't really find anything except people's posts in forums. Nothing scientific.


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## Dman1234 (Oct 26, 2014)

you will lose 6 hours a day at 18/6. thats 3.5 days every 2 weeks of veg lost. 24-0 is the only way for me.

the proof is in the fact that so many run 24-0 without issue so why throw 25% of your veg time away.


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## Locked (Oct 26, 2014)

Dman hit the nail on the head.  MJ will grow the whole time the lights are on.  So any dark time is lost veg time.  Other than for triggering the production of Flowering hormones a dark period is not needed. Jmo


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## Rosebud (Oct 26, 2014)

Good post DMAN!


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## The Hemp Goddess (Oct 26, 2014)

I agree with Dman.  I don't know why cannabis doesn't require a dark period, but I found the same when growing greens (I grew hydroponic lettuce last winter under fluoros).  It will grow all the time the lights are on.  So, by shutting the lights off 6 hours a day, your plant is getting 25% less veg time and to make matters worse, it will stretch during the time the light is off.


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## Hackerman (Oct 26, 2014)

So, this is true of ALL plants during the veg cycle?

If this were true, I assume all the nurseries run their indoor stuff 24 during veg of all their plant? Hmmmm? 

This needs a little research.

Where is umbra? (lurking in the direct shadow, no doubt). LOL

Rather than tick everyone off again with questions that you don't have the answer to, I'll find out and post back. 

OK, I have to say it..... "If everyone else jumped off a cliff, would you?".

Sorry, my Dad made me say it. LMAO


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## Hackerman (Oct 26, 2014)

Going to post a few notes here. Not looking for answers. Just don't want to loose this info.



short-day facultative

©The photoperiodic response is controlled by phytochrome. "Phytochrome is a blue pigment in the leaves and seeds of plants and is found in 2 forms. One form is a blue form(Pfr), which absorbs red light, and the other is a blue-green form(Pr) that absorbs far-red light.

http://www.globalsciencebooks.info/JournalsSup/images/Sample/PS_4(1)5-17o.pdf

_One way in which plants are categorized is by the way they gather and handle carbon dioxide. Cannabis is a C3 plant. It uses the CO2 it gathers during the light period, when it is photosynthesizing. Plants designated C4 also gather CO2 during the dark period for use during the light period. Many C3 plants, including cannabis, do not need a rest period. They continue to photosynthesize as long as they are receiving light. _

_Yes, plants do need darkness to grow.
First, in the photosynthesis process itself, there is a reaction known as 'dark reaction' pathway or lately known as 'carbon reaction' pathway where the free energy of ATP and reducing power of NADPH, are used to fix and reduce CO2 to form carbohydrate. This is very important process to release Oxygen into the air. This happened in the dark or at night_

http://www.csrees.usda.gov/newsroom/research/2007/sleeping_plants.html

http://biologicalexceptions.blogspot.com/2011/11/plants-that-dont-sleep-will-take-dirt.html

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Photoperiodism.html


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## The Hemp Goddess (Oct 26, 2014)

Doesn't that kind of contradict itself.  Many C3 plants...do not need a rest period.  And then in the next paragraph:  Yes, plants do need darkness to grow.  These 2 statements are not compatable...so which is it?

I can tell you that decades of growing has convinced me that cannabis does not need a dark period.  It will grow with closer intermodal spacing and more bud sites with 24 hour light rather than 18/6.  I do run shorter vegging hours sometimes in the heat of the summer and the plants are never healthier or bushier than those run at 24/7


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## Hushpuppy (Oct 26, 2014)

Cannabis has learned to rest in the light and take cat naps to help it grow without a dark period :doh:


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## Hackerman (Oct 26, 2014)

I am still reading on it but it seems some plants (potatoes, tomatoes among others) require the night cycle while other plants (cannabis included) do not require a night period.

The science is still somewhat undiscovered and the hormone changes are not 100% clear. Lots of theories. Most of them similar and mostly based on the facts they have. Still, there's no solid answer as to exactly WHY.

One thing I did read over and over is that during the night cycle, most plants (including C3 plants [cannabis]) exhibit stronger root and stem growth when subjected to a night cycle of at least 4 hours.

This info coincides with the post made here earlier by [don't remember which member] that said they had better root growth while cloning with a 12/12 cycle.

So far, what I have summarized from the reading I have done, there is no reason to include a dark cycle while vegging cannabis but a 16/8 or even 20/4 may show stronger root growth during cloning and early growth.

I am still reading.


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## Hackerman (Oct 26, 2014)

The Hemp Goddess said:


> Doesn't that kind of contradict itself.  Many C3 plants...do not need a rest period.  And then in the next paragraph:  Yes, plants do need darkness to grow.  These 2 statements are not compatable...so which is it?



Like I said earlier, those were just notes. The reference to plants that need dark period was from a nursery site and I believe they were referring to chrysanthemums.

That's why I said to ignore that post. I was only interested in reading and understanding the part that said, _"free energy of ATP and reducing power of NADPH, are used to fix and reduce CO2 to form carbohydrate"_.

It wasn't in reference to cannabis.


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## 7greeneyes (Oct 27, 2014)

One less timer to worry about. 24-0 on/off for sure during veg.


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## The Hemp Goddess (Oct 27, 2014)

I personally have never seen better anything with 18/6 rather than 24/7, including the root growth.  One of the things with DWC is that you can always see the size and health of the roots..


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## Hushpuppy (Oct 27, 2014)

Hey Hack; The chemistry of photosynthesis is truly amazing to study. I have been an electronic tech ffor over 20y and I discovered that electrons rule the universe. ATP and NADPH are molecules that are made by the plant to be electron carriers. In photosynthesis, the energy in the photons of light is used by the chloroplasts to release the free electrons in molecules of "energy nutrients". The separation of the free electrons breaks the bonds holding the atoms together in the given molecules. 

These free electrons are then stored in ATP and NADPH while the broken molecules are moved out of the space to allow for more to come in to continue the process. In other places within the cells of the leaves, the different "broken" elements are reassembled using the free electrons that are held in the ATP and NADPH. The new molecules are carbohydrates and other important chemicals that the plant must synthesize for itself.

It is fascinating to study but a bit tricky to wrap your brain around sometimes.  And don't even try to get it while stoned :huh:


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## Hackerman (Oct 27, 2014)

Awesome explanation. Thanks a ton.

There is a lot to it. I usually get pretty deep into my hobbies and I don't expect this will be any different.

Although, I do see one problem...... "_And don't even try to get it while stoned_".... could present something of a problem. LMAO

Thanks again for the great explanation.


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## DogBoy420 (Nov 1, 2014)

Back when I used MH lighting for veg, I vegged 18/6 because of the heat.

Then I switched to T5s for vegging and went to a 24/0 veg schedule.  With good results.

Now I'm 100% LEDs (for veg and flower) with a 24/0 veg schedule with good results.

Use 18/6 veg only if you have heat issues during the hottest part of the day.


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