JonnyBlazeOne$
Member
Do u guys run high CO2 til the end ? I usually run at 1200ppm til the end but have read it can hinder ripening n quality Thoughts?
Co2 during last 2 weeks
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SchmoeJoe
Well-Known Member
It is known to suppress ethylene production in some plants. I don't know if it's been confirmed that cannabis is affected that way. I worked at a commercial rec farm that ran 1500ppm all the wat to day of harvest and some strains never stopped growing or entered into the kind of development you'd expect to see in the last two or three weeks. That was enough to convince me.
ttystikk
Well-Known Member
Counterpoint; I ran 1200-1500ppm from beginning to end of bloom and never saw it hinder development, across many dozens of strains. They all ripened nicely for me. I ran somewhat warmer, more humid and brighter (higher PPfD) conditions than most and those may have been contributing factors.
SchmoeJoe
Well-Known Member
We ran 1500ppm at 85°f/70%rh for optimal co2 utilization amd textbook ideal vpd for optimal nutrient uptake and dialed ppfd in with an apogee quantum meter. The strains that showed the inhibited (spelling?) ripening were strains that were already known for going long and continuing to throw fox tails even when they were done.
On a side note, they rarely broke 1.5 per light, told us that botrytis was normal in indoor weed (70%rh), and the quality was so great that they wholesaled most of it at 700 a unit even though tbey owned five dispensaries in the biggest markets in the state.
nxsov180db
Well-Known Member
70% rh even at the end? yeah that's a problem..
SchmoeJoe
Well-Known Member
They also told me things like "Spider mites don't hurt plants", and "You can't start seeds in soil".
Some people keep CO2 at 1200 ppm until the end, but I personally drop it to 800 ppm in the last two weeks. High CO2 can slow down ripening since the plant focuses on growth instead of maturing the buds. Lowering it helps bring out terpenes and final quality better.
ps.
I’ve tested it myself – keeping 1200 ppm till the end gave me big buds, but they seemed less aromatic. XD When I lowered it in the final weeks, the flavor difference was noticeable. Test what works best for your setup – every grow is a bit different.
Mumbeltypeg
Well-Known Member
Same here, had the constant growth issue, full coverage foxtails running 1500ppm and 1500+ppfd.. now I back off and slow down coming toward the end.
nxsov180db
Well-Known Member
It's your 1500ppfd that I would say caused foxtails, co2 not so much.
Mumbeltypeg
Well-Known Member
It could be strain/temp dependent also to be honest, I have run full strength lights at above 1500ppfd with some strains and had massive healthy buds no foxtails, and others that just seem to want to keep pushing out new growth and not finish/swell properly.. one argument was that co2 suppresses ethelyne production and hinders ripening of the flower.
I was just listening to This interview where he says they can crank the ppfd over 2000 and have a linear increase in yield.. no mention of foxtailing, would have been nice to ask some questions.
Mumbeltypeg
Well-Known Member
Now that I think of it, it could be more to do with the flower temperature itself..combination of ambient temps being too high and lights too close heating up the temperature of the actual bud causing it to pop out foxtails. I’m going to start writing down flower temps from now on.
Yeh, flower temps are a big deal, especially in CO2. Westmoreland, now Dr Mitch, did the original research back in 2021.
I've attached a copy of his thesis. The CO2 work is one of the chapters. Lots of good info in there.
