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48hrs of darkness before harvest

marcopolo

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Hello,
I’m days away from harvest and wondering if anyone has any feedback on 24-48hrs of darkness before harvest. I read this recommendation in a few growing books.
 

The Hemp Goddess

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I really have never read this or done this.

What is their rational for doing this? Is there a scientific reason?
 

Bubbletrouble

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Yes please enlighten me on the science behind that. I would like to know because im not understanding whats going to happen in that small amount of time with lights off that wouldnt happen better with lights on.
 

cardgenius

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The theory goes, trichome production happens at night therefore putting it in 24-48 hours of darkness will give it a boost just before you harvest.
 
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Bubbletrouble

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Hummm,,,not sure about that. Seems that would happen better with lights on,,but im not a Botanist.
What i do know is the weaker the light the less Trichrome production,,so im not sure how Trichrome production would be better with a 48hr dark period.
I did a ton of reading on this and 95% of the growers said its total bull manure.
 
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cardgenius

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Hummm,,,not sure about that. Seems that would happen better with lights on,,but im not a Botanist.
Yeah, I think of it as a growers old wives tale/myth. Seems like there’s a lot of misinformation out there that goes unchecked and gets passed around easily.
 

WoodsRat

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I saw the same article a few years back, so I tired it. I couldn't honestly tell any difference between 48 hours of dark before harvest and normal harvest. I also tried the "nothing but water" flush while growing hydro. Absolutely no difference in taste or buzz.
The dark cycle would be an easy one to try if you wanted to. Harvest all most all of your plants, leave one or two, and turn off the lights. Go back in two days and finish the harvest. After they all cure, see if you can tell a difference. I couldn't.
 

stinkyattic

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The rationale I've heard for this is a different version; that light destroys THC.
While it is true that uv radiation decomposes hydrocarbons of all sorts, it's not like you've got a crazy intense uv lamp in your grow room lol.
Dark cycle is just one more overcomplicated overhyped YouTube clickbait-hooey theory.
 

spaade

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As I plant physiologist and biologist specializing in cannabis I can assure you that the "48 hour light depravation" prior to harvest is typical "street" mythology and Youtube bull. One aspect of trichome production in cannabis is protection against chromosomal mutation and DNA damage caused by UV light, particularly UVC by shading the surface area of the leaf and flower lessoning UVA, UVB and UVC light penetration. Therefore, more light equals more trichome production which equals more THCA and more ∆9-THC production at the cellular level within the trichome. 48 hour light deprivation would actually slow down trichome production hence slowing down THC production.
-spaade
 

Steve1

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What I have heard has nothing to do with trichomes I heard that by turning off the lights, your basically “turning off” the plant and some of the nutrients and chlorophyll in the plants settle to the roots. While that sounds reasonable, I think it would take a lot longer than 24-48 hrs. I did it my first grow because I knew no better but I don’t do it anymore
 

stinkyattic

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Correct; and as chlorophyll breaks down, an actively growing plant will scavenge and redistribute the released nutrients through its vascular system to where it is actively trying to grow- its reproductive parts.
There's a reason the sugar leaves are the last to yellow on a severely malnourished plant approaching harvest. Those buds awaiting pollination are that plant's last hope to breed for the next season.
You can't really game biology on this one; )
 

marcopolo

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This was always a head scratcher, but now it’s clear to be an old wise tale. I read this is Jorge Cervantes growing bible and most of this literature is very useful, but the 48 of darkness allows floored me.

Anyways, I didn’t do the 48 of darkness. Just harvested like normal. Looking good so far. Wet trimmed, and in the dark dry room at 68F and 55 humidity.
 
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