Growing Plants to reduce THC from 0,39% to <0,3%

Hy Icmag, after years of silent reading, finally my first post.
Without you guys, I´d´ve maybe never gone vert.

In my Area theres a law, that Cannabis grown for CBD must be under 0,3% THC & THCa.
I can get Clones with a total Amount of THC of 0,39%.
Is there a possible Way to trick the Plants into producing a little bit less THC?
The testgrow where i got the Lab results from, was pretty dialed in.
Indoor under 1k hps in COCO DTW. They tried to get the best Results possible.

My first Idea is, to let the Plants ripen a little bit longer, to turn the exessive THC into CBN. Is this possible?

Is there a rule of thumb, when max THX is reached? Maybe cutting them a week earlier could also solve the problem.


Indoor they´ll get Light from some 600 hps, sitting in rockwoolcubes on a NFT system. Tap EC 0.5 + EC 0,7 Canna Aqua. The system is prefered, but not madatory. Would even go back to Soil, if needed.

Theres also a organic outdoor grow planned in soil.


Hope you guys can help me find a solution.

greets lectron

Check out this study which correlates available Nitrogen and THC production.

http://druglibrary.net/olsen/HEMP/IHA/jiha4207.html

These experiments show that the THC content of leaves decreases with increasing N doses. This phenomenon is favorable for agricultural production, because nitrogen fertilization will increase stem yield and simultaneously decrease THC content of the plant significantly. Additional studies are necessary to determine optimal N dose/ha, time of application, fertilizer type and the lowest THC content achievable under field conditions.

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Very interesting Paper

THC was highest in leaves near the shoot tip and on side branches, and lowest in oldest leaves

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Okay, Flowers are the last parts developing in a Plant, so the THC levels will be the highest there. Thats my first conclusion. Sadly they meassured the THC levels only in Leaves. But my first assumption is, that letting the plant ripen longer than necasarry could decrease THC levels a tiny bit.
measuring this effect is doable for me. I guess harvesting a plant every 3-4 Days after flowering-day 55 could get me rough (considering testing different buds at every harvest-point is to expensive for me) results .
Is there a cheap way for meassuring THC levels, beside liquid chromatography in a lab?


The difference between a2 and a3 is very small. But hey, maybe there is a bigger drift when comparing Buds at different days of flowering.


Increasing N levels looks more promising.


b1 got 1,223 times more THC than b3.
Compared to the strain offerd to me, THC would drop from 0,39 to 0,319.
This looks like a promising decrease
My only concern is, the breeders grew the labtested Plant in Coco.
I got no personal experience (can just repeat what i read in diffrent growreports), but most coco-growers work with skyrocketing high Ec, compared to my recirc NFT and E&F.
Even if they use PK-Boosters, the N in their solution could be pretty high.

Is there a mediumless System, which is more suitable for high N rates?
getting myself a RO-Filter would be my first Idea, to feed more, while staying relativly low with the final EC.

My understanding is that UVB level correlates to THC production, so you could try getting some custom LED setup where there is almost no UVB. Might lower that THC the little bit you need.

would this be on the cut called cherry? same thing here in my state, its 3 percent and all i see around is this cutting called cherry? pm if rathcer not chat in forum, im new to this hemp cbd but friend has a permit, trying to find him some different cuttings under .3 , thanks, also id say let it go longer than a week, goto 70 days , then test a sample might be less

shawkmon said:

would this be on the cut called cherry? same thing here in my state, its 3 percent and all i see around is this cutting called cherry? pm if rathcer not chat in forum, im new to this hemp cbd but friend has a permit, trying to find him some different cuttings under .3

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I don´t know the strains name, but could be a CBD Therapy selection. total CBD is arround 11%

I think I don´t got enough posts to send you a pm.

I already found 3 supplieres for Phenos with THC <0.3%, but the minimum order quantity is to much for just myself and my growing style. But it looks like we can get 2 legal outdoorlocations.
Maybe your friend is interested in ordering together.
reading about his 0,3% limit, it could be possible that he´s also from europe

Beside that, we´re running a slection grow from eu-aproved strains. But its only end of flowering week 3 atm, so final results will take some time

ah im usa

I love that now we have threads on decreasing THC. Very interesting stuff. Thank you and
good luck