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Dark period before harvest

Locrian99

Locrian99

New member
Curious what people think of the 48 hour dark period before harvest. I know some do it, it’s not necesarry has anyone for sure seen benefits from it as opposed to that’s just always how I’ve done it? I’m curious the same for drying. Obviously don’t have a bright Light right on them. But does the room need to be black, or can there be some light. Thx all.
 
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We were discussing this on another thread, but I agree it deserves its own.
I will summarize what I have learned through fairly extensive research.
Cannabis is a C3 plant. As such it does not need any darkness during vegetation. The Calvin cycle, which is sometimes known as the "dark cycle" operates in C3 plants all the time or they are dead. It is inaccurately called the "dark cycle" because it does not need light, however it also does not need darkness.
During light, your plant produces sugars and other chemicals needed to run the Calvin cycle. Your plant stores a portion of these for use when there is no light so that the Calvin cycle can continue and the plant doesn't die.
Now the interesting part...
The production of most cannabinoids is powered by the Calvin cycle. So they are being produced 24 hours a day in the later part of flowering even though the lights are on only 12 (or less!?). Light actually degrades compounds like THC. In some parts of the plant, light degrades them faster than the plant can produce them. Thus, your plant is making THC all 24 hours, but a portion is burning off when the lights are on. You need to keep running the lights so that the plant can do all that it needs and recharge its reservoirs to power the Calvin cycle. But at harvest, you no longer care about the long term health of the plant. Leaving it in extended darkness depletes you plants reservoirs as it will continue powering the Calvin cycle (and making THC) as long as it can.
The above is also why most growers harvest in the morning or before the lights come on, even if they don't do extended darkness.
If you are growing Autos and leaving them on long days up to harvest, I would also consider this carefully.
I plan to increase darkness to 14 hours for the final weeks of Flower and will leave the plants in darkness (if I can, there are more than one) for 48 hours before harvest.
 
Thanks camp appreciate the explanation rather than yeah you should. I’ll bump darkness to 14 hours tonight. Planning on harvest Sunday. At which point I just won’t have the lights turn on Friday. Guess I’ll check her Thursday night and make that decision.
 
No problem Locrian,
Sounds like a good plan.
Your talking about the GG4, right? Be sure to post some pics when you check her on Thursday! I'd love to see what she looks like before harvest!
 
I cannot speak with any authority about the impact of limited light while drying. I would defer to experience, but don't see why it would be an issue if it isn't powerful and is indirect. Darkness certainly shouldn't need to be respected like it is during flowering
 
When drying avoid direct light but, I find that temp & humidity much more crutial. The old ones always said the best place to dry herbs is in the hayloft. Too bad we all don't have one of those puppies.
Be good, G
 
Have not darkene them last couple harvest. If anything, plants seem a couple of days better. If that makes sense.
 
I quit feeding an watering my plants 2-3 days before harvest, so the dry only takes 4-5days not a week, hang them in the dark 2-3days in a closet. Then brown paper bags ,gently shake the bags every day a couple of times, the bags have Hydrometer in them, when close to 50-60percent humidity I put them in jars with Bovedas.
My outdoor plants we cover up totally with black plastic an do them the same. No scientist, but I can promise you ,you'll see alot more trichs if you keep them in the black dark a few days before chopping.
 
@ campesino Can u please direct me to the base of your findings because I have read scientific papers done in labs that say a dark period does nothing and light does not degrade thc. I would love to read the science u have because it contradicts everything I have been reading from the science community.
 
I hung my current harvest, first half of Death Star in my veg closet with the lights going on and off because I had no idea about all of this. I took all that shit down, and will now do what you just said, DAAS.
 
I’m leaning towards for sure trying the dark. Hopefully the humidity doesn’t get too high, I see a pretty good jump during lights out and of course we are having our wettest week since last winter this week. Last two plants in the tent, so it’s an easy enough option. Drying I might do in a large cardboard box cut a few holes for air flow. No closet in basement and don’t really want to dry on main floor or upstairs around my son.
 
Hasn’t led me wrong yet. I’m for sure trying it with my 2 gg#4s I’m planning on chopping Sunday.
 
@abadtrip
As I said, I am going to work to put together some notes and citations on this. I have been poking around during free time today, but will need some time to pull things together and be able to share sources. It feels more like work, and I actually have enough of that right now, so I'll do my best. In the mean time, I want to reiterate my confidence in the information I provided.
Something about your comment has bothered me today. You are asking to know my sources, but didn't share your own. Your comment challenged the veracity of the information I provided by making reference to "scientific papers done in labs". Your challenge obligates me to respond with my sources. I feel you should be similarly obligated to share yours.
I am an academic and "affiliated" with a university. I have access to journal articles. If all you have are citations, I will be happy to fetch the articles.
 
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