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Darkness before harvest

RosettaStoned

RosettaStoned

New member
So I forgot to turn my light off Monday night. I was going to harvest tonight but they will only have been in the dark for 12 hours. I should probably wait I'm assuming?
 
I would give them at least 24 hours in the dark. 36-48 if you feel like waiting or if it better fits your schedule. From what I have read (a lot) and understood, 36-60 seems ideal.
 
Why can some 1 please point me to the science that says this works I want to read what u guys are reading I have found nothing on this in a scientific paper that has been through pair review and please if u have done it yourself and would like pair review send me your papers and I will run the experiments i am getting close to harvest so its a good time
 
Hey Abadtrip, i quit watering an put mine in the dark, 2-4days, an if you look at the trichs real good before, you put them in the dark, an look at them again after the dark, the trichs just look alot bigger, an taller, . I aint got no scientific proof though, but im gonna continue to do it anyway. Good luck on your harvest, you ought to try it on one. Just to see if you can see a difference.
 
I know what u see may look good but is there any more thc contained in the bud is my question I understand that they look more frosty but is there any more thc. I think I am going to find out get some test kits and do a comparison. I have to know this is 1 area where folk law seems to Trump science.
 
My next grow with clones I'm going to try this. It won't be peer reviewed, but it will be with clones that are going to be in the center of my tent, in the same conditions, same feed schedule, with before and after shots before harvest. It won't be peer reviewed besides a few folks on a fourm. But from what I've seen from some of the folks on fourms, scientific peer reviewed papers aren't as good as regurgitated dogma.
I got into a discussion a few days ago about ppfd and even though I posted just one of many study's done by ole Miss, that still wasn't as good as the "lighting sub-fourm helpers" word.
 
It has to do with the long darkness period creating stress on the plant. Which in return floods them with goodies. Its a last ditch effort by the plant to finish and survive. Luckily its at the end of flower and will not affect sex/pollination.
 
the way i see it, the only pro i can reasonable believe from doing this is based on two very basic truths of cannabis. the first is trichomes are a protection from the light and only grow during the night. the second is trichomes are degraded (oxidized) and the THC turns into CBN (amber trichome) lowering the perceived potency, this process is accelerated by light and heat. so my reasoning is when you have a plant ready to harvest it means the trichomes are in its peak maturity, so leaving them in the dark and not watering will allow the plant to use the energy stored inside the plant to create more protection from the sun (lack of water i imagine also has to promote sun protection) but without the deteriorating effects of having high light and heat levels, therefore one could deduct the overall technique does give the plant another couple of days to work with what it already has and stop the trichomes from going bad. again this is my opinion and reasoning, ive done it in the past a few times and some other i didn't do it, i personally think it doesn't make much of a difference. i imagine it like this: imagine the day you harvest, now think two day before that, the whole benefit would be how much the trichomes "grew" in those two days plus the trichomes that would have otherwise went amber in those two days. i hope i didn't just ramble randomly and made some sense (:
 
Makes good sense to me 9fingers, like I said ,I ain't no scientist, but when I see more an larger trichs, I'm happy. Lol.
 
abadtrip did you see the additional comments I left for you the last time we discussed this?
https://forum.growweedeasy.com/forum/growing-community/167116-dark-period-before-harvest
I would really love to see the "scientific papers done in labs" that you mentioned. As far as I can tell, there is no publicly available peer reviewed research that specifically tests this, so if you have scientific papers done in labs, please share them.
I am happy to answer your questions about the plant science part - but experimental data is not available.
 
campesino that’s some good info I dunno where I heard trichomes developed at night but I believe you thanks for clearing that :)
 
Well I am just going to have to do it see for my self I grow autos under 24 hrs of light so I should see a huge difference at harvest after 36 hrs of darkness.
 
9fingerleafs I bet I know where that thought comes from. Cannabinoids are powered by the Calvin cycle. The Calvin cycle is often known as the "Dark cycle". This is because early in the history of plant science they were able to determine that this cycle was happening during the dark. But it doesn't just happen during the dark, it happens all the time. The fact that it is called the "dark cycle" has led to a widespread belief that Cannabis plants need darkness to do certain things. I came across this misconception repeatedly in forums discussing Darkness (both dark periods during veg and dark periods prior to harvest). The only thing Cannabis needs darkness for is flipping its cycle to flower, and that is independent of photosynthesis and the Calvin cycle. As you correctly point out, the benefit of Darkness prior to harvest is that the plant doesn't need light to produce THC, at least for a while... The plant has enough stored sugars to power the Calvin cycle for at least 60 hours of darkness, during which time Cannabinoids are being produced and are not being burned off.
 
I am going to cut tonight since the troops are called in for it. We won't finish, so I can see if there is a difference from one day to the next. They'll be about 16 hours in the dark when I get to harvesting. Tomorrow will be 40 hours.
 
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The 60 hours of darkness thing sounds interesting to me. Maybe 7, 24 hour light and 50 hour dark cycles I think would be a worthy experiment.
 
abadtrip I understand your desire for peer reviewed studies, we would all like to see that data. If you are interested in an experiment and can set up four scenarios with Autos, this is how I'd set-up the "experiment"
Group 1 (control): Run these as you normally would (24 hours of light right up until harvest?)
Group 2: 24 hours light and then 48 hours darkness before harvest
Group 3: Gradually increase darkness over final two weeks. run light 12/12 or even 10/14 (on/off) for last 4-5 days, harvest at end of 12 or 14 hour dark period
Group 4: Same as group 3 with an extended darkness of 48 hours before harvest
My hypothesis is that group 4 would test the strongest and group 1 the weakest.
 
"The Stichting Institute of Medical marijuana (SIMM), the first company to sell marijuana through the pharmacies of Holland, has been investigating the medical possibilities of cannabis, together with TNO laboratories and the University Leiden."

There has only been a small research effort into the subject of darkness before harvest, but it produced some interesting results. They found that seperating their crops and harvesting half after 72 hours of darkness, showed upwards of 30% increased THC in "some" strains. CBN and CBD were no different.

At night plants follow a cyclic function that operates differently compared to during the day. They accurately and mathemetically calculate how much photosynthate to burn for their duration of darkness. This calculation has been observed in plants and that they can accurately utilize photosynthate so that it is almost completely exhausted before light arrives. After which so a unanticipated duration of dark would send a plant into starvation mode.

The exact relationship of THC production is not completely understood, but it has been thought that it is used to protect itself from light. As such THC degrades with light and is continously being produced. So it might be plausable that darkness before harvest increases THC levels in plants, but i would anticipate based on current research that this effect would not be well benefitted past the standard 12 hours of darkness. As it has been shown plants degrade 95% of their stored resources by the time of their calculated night cycle is nearly finished.

I would personally still use 24hrs or more of darkness before harvest, as there are other properties that are of benefit.
 
Hi DANGERDAN do you have anything on the SIMM studies first hand? I have seen comments about their studies and the 30% claim in several forums, but cannot find anything that suggests the studies are real or have ever been published. The earliest claim I could find was in a RIU thread and I sort of personally concluded that the guy who posted it probably made it up. If these studies are real and are available I would love to know about them. I have access to any journal article, so please let me know if you have citations.
The stored resources link is interesting to be sure, but I am not convinced it is as significant. It depends on the way that Cannabis cannibalizes itself during starvation mode. I know that putting them into extended darkness is not good for the plant and will kill it. The question is how long does that process take before it starts to negatively affect the flowers. Flowering plants will protect the vitality of their flowers at all costs - even death. There is certainly a limit though.
 
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