When to Stop co2 Increase During Flowering?

Discussion in 'Advanced Marijuana Cultivation' started by Micobfsb, Nov 29, 2011.


    Thedillestpickle Well-Known Member

    I just added this thread to my favourites list...

    CO2 will not raise your humidity, if you use a CO2 generator(propane or natural gas burner) then yes your humidity will rise, but the same is not true for a CO2 ejector.

    During the last two weeks of flower its a good idea to lower your temperatures so that you dont volatize the very nice aromas of the bud. You can keep running them high for the sake of yield but for higher quality you should lower temperature to normal levels. Now that your temperatures are back at normal levels theres no need for the extra CO2.

    Flourecents can be used in conjunction with CO2 but only if you have alot of light, Usually if your running that much light you have invested in a HID, but some people will run alot of light using just flourecents. This myth is actually stated with no explanation in the growers bible by Jorge Cervantes, His book is alright but its full of misinformation

    Hopefully Im not full of misinformation(bullshit), everything I just typed is speculation
    Dr. Who likes this.

    IVIars Active Member

    By decreasing the co2 levels toward the end, i believe it stops ethylene (sp?) production and begins ripening it.

    Warmer temps when running co2, 80 and above.

    Too much humidity cause the trics to become elongated and make it easier for them to snap off

    xmatox Well-Known Member

    Lol. You're funny.

    DirtyEyeball696 Well-Known Member

    I use co2 all the way until the last 7 days of flower. The biggest thing to keep an eye on is the humidity. 45-50% is optimal

    Kush is My Cologne
    Dr. Who

    Dr. Who Well-Known Member

    KEEP IT BELOW 70F or risk loosing everything to root rot!
    DemonTrich likes this.
    Dr. Who

    Dr. Who Well-Known Member

    You stop at 2 weeks left so the ethylene gas starts to be expressed by the plant to actually ripen the bud! It is connected to the bulking phase and if you don't stop it's use (CO2) the plant will take longer to actually ripen and it decreases the potential yield!

    The use of CO2 in veg is NOT worth the cost of doing it! Sure your supplier is going to say to! He's the only one actually GETTING any "profit" from it!

    You read above right?

    And you guys believe this SHIT! For god's sake you don't even go out and find the truth? Best info on this subject is in Ed Rosenthals book "Marijuana Growers Handbook" PAGES 131-142 and 192-193.

    Did you read everything to this point? DO IT!

    What crap! Running gas in veg is THROWING AWAY MONEY!

    GAS OFF FOR THE LAST WEEKS - Nothing to do with "OILS"....... YES! Higher temps and RH in bloom for gas to actually WORK right! I run 1300ppm with about 85- 87 F and 70-80% RH. You cool to normal at lights out.

    What the fuck? This is BULL SHIT of the highest order! Please list your source for this - I want to know!

    EW, EW,,,,,SO close! "starts" the ethylene to become effective at ripening!

    I might start at 80 F for 1150 ppm and have 85+F by 1300!!!

    WHOOPSY! Wrong answer! You MUST run higher RH right along with the higher temps to maker the high ppm rates of the gas to BE effective!

    I hope you all read your personal answers!

    Here is an example :

    Your running, oh lets just say 1500ppm of co2 - to make the point here..
    You have 5000 lumins of light (645w per square meter)
    Your temp is 70 F
    The plant is only up-taking or "using" 800 of those PPM!!!!

    OK, same set up BUT,
    Your temp is 85 F
    The plant is now up-taking 1300 of those PPM!!!!!!

    NOW THEN: A word on higher RH with gas use.

    Alright then guys and gals Have you ever heard of the VAPOR PRESSURE DEFICIT?

    I borrowed this for my ease -

    RH has an ever more direct effect on plants. Plants need to "sweat" too - or rather, they need to transpire (release water vapor through their stomata) in order to grow.

    The amount of water plants lose through transpiration is regulated, to a point, by opening and closing their stomata. However, as a general rule, the drier the air, the more plants will transpire.

    RH has an ever more direct effect on plants. Plants need to "sweat" too - or rather, they need to transpire (release water vapor through their stomata) in order to grow.

    The amount of water plants lose through transpiration is regulated, to a point, by opening and closing their stomata. However, as a general rule, the drier the air, the more plants will transpire.

    TAKE a LOOK at this chart!


    Now while I run only 45% RH at say 75 F with NO gas.
    When I run gas, I have to be FAR, far closer in the VPD for the co2 and plant work at it's best together!

    CO2 increases uptake. This means your getting more nutrient, right along with that water!
    By this factor of increase (about 30%) you NEED to balance much closer that VPD to not begin to feed too much.

    When I run my generator. I have a temp of 85-87F and an RH of about 70-75 during gassing hrs...

    Understand this ?

    PLENTY of scientific PAPERS available on the web to read on exactly this subject and it's parts described here!

    Start looking!
    Rasta Roy, Jubilant, linky and 2 others like this.
    Dr. Who

    Dr. Who Well-Known Member

    You better read the above post as punishment for duping me into answering a 4 year old post! You should find your RH is too low!
    Rasta Roy likes this.

    thewanderingjack Well-Known Member

    And thats a big yes because:

    Except not begins, allows to begin... CO2 inhibits ethylene production, a fruit hormone/pheromone that induces ripening and is produced by ripening plants. Transport trucks use low temps and CO2 to transport produce to reduce the risk of spoilage.

    "one bad apple spoils the bunch" is a metaphor based on this literal effect.

    p.s:. remove ripening fruit from other fruit, preferably completely away, to extend the other fruits life... a ripening fruit will ripen other fruit.

    you don't ventilate well in and around each plant... I run that high or higher (my environments very wet) and only have problems when I have overlaps or just not enough air circulation... both by pulling branches out via LST and by having a nice fan blowing. I just went through my plant super close... only problem I found was where a plant had had a branch up against the wall (just a small spot).
    Last edited: Aug 3, 2016
    Dr. Who

    Dr. Who Well-Known Member

    You do know I was talking about DWC right?
    One day you'll hit a strain that will NOT hit a 70F res temp without getting root rot. Can you say Bomb Seeds? That's just off the top of my head.......You do not allow res temps to go over 70 F....general accepted temp across the board....

    thewanderingjack Well-Known Member

    Hah, I did do and had forgot... so yeah... I should sleep... it's been a while. :-D I'm sure I was even referring to bud rot.

    Root rot, in DWC, I know nothing about... but just to note: in soil, it is just as serious... most people in general, and newbs in particular, "over water" and wind up drowning their plants.

    Thanks for the heads up :-D... hate to be accused of talking out my ass (and having it be true!)
    Dr. Who likes this.

    b4ds33d Well-Known Member

    the bro science is strong with this one.
    Dr. Who likes this.

    powerslide Well-Known Member

    2012 brought back to life to call some dude out and disappear. Nice

    xmatox Well-Known Member

    Disappear? He never responded to me probably because he was here for about a day and left. I did however bring back this thread from the dead. My B bongsmilie
    D port Growth

    D port Growth Well-Known Member

    Schooled... he hit them with the VPD for the killshot.

    organixx325 Member

    Dr. Who is the man, thank you for the input and correcting all the assumptions floating around. Just setup cO2, temp running at 85-88 above canopy and trying to get my RH up to 80%. I may need another fogger,

    linky Active Member

    I just started my new room and have learned about VPD myself very recently. I am running mid to high 80's canopy temps and 1250 ppm of co2 with ~75 percent humidity. I am curious though how long in flower people are using the VPD chart, all the way through or only the first few weeks of flower? I am about 4 weeks in right now.

    The first two weeks of flower I was unaware of VPD and was running mid to high 80's at ~50% humidity and 1500 ppm of co2, and the plants actually did not look good. I thought it was a nitrogen deficiency but after researching I think it was partially to do with VPD, to high temps and much to low humidity. Granted I am also running strains I have never grown and complete new hydro system and nute line.. so tons of my factors all at once.

    Now that I think I have my environment doing pretty good I am just curious how long I should be running those temps and humidity, I am thinking the last couple weeks I should lower temps a bit and lower humidity to avoid bud rot. So far I have had zero issues with PM.

    DirtyEyeball696 Well-Known Member

    I run my co2 burner at 12-1500 ppm
    It's awesome and makes my plants grow so much better. 85-95 degrees won't hurt your plants but make sure you have proper circulation

    Kush Is My Cologne
    CaptainCAVEMAN likes this.

    DirtyEyeball696 Well-Known Member

    I'm not up much for charts, but I am interested in growers who use co2 & their input

    Kush Is My Cologne
    Peter Vakomies

    Peter Vakomies Member

    If you have enough light to drive the 'extra' photosynthesis, always enrich with CO2, right to the end.

    Just a few facts about plant physiology to consider:

    All green parts of the plant, every green cell there is, are trying to fix CO2, and capture it and build the CH2O carbohydrate into the 'body' of the plant. Even green buds, stems and calyxes fix CO2 into CH2O's. The whole green plant is starving for CO2.

    Remember - 45% of the dry weight of a bud is made of carbon, and it all came from CO2 in the air! That's almost half of the dry weigh of our crops is carbon alone, so CO2 enrichment works; it will increase yield if you have high enough light levels.

    The leaf temperature is always warmer than the air tempearture. 85 deg F in the air is 90-92 deg F on the leaves... To increase VPD, which makes plants transpire more, just cool to 70 Deg F with air conditioners. A 70 Deg air temperature is a 75 deg F leaf temp.

    Cooling the air with AC's dries the air alot, so AC's pull the water out of the plants, the operating AC's are 'growing' the plants too!. Transpiration equals growth; the plant that uses 10 liters of water a day is growing bigger than the plant using just 2 liters a day. With unlimited water in the root zone, stomata are open, and CO2 pours into the plant.

    Also plants always acclimate to a high level of CO2, they get 'lazy' and make way less RUBISCO enzymes if exposed to high CO2 levels all the time. This enzyme is the one that 'grabs' CO2 from the air; plants won't invest in making more RUBISCO if the CO2 level is high. This has been studied in detail, as RUBISCO is the most abundant enzyme on Earth; it enables all life!

    Inside plant cells there are way more RUBISCO enzymes to take a 'gulp' of CO2 from the air if CO2 is running at 500ppm, than when plants have been growing at 1500 ppm CO2. These enzymes cost the plant to make, and their turn-over rate is fast, they aren't synthesized in the dark, and will even be broken down at night. In the day time plants make as much RUBISCO as they 'think' they need.

    So if you vary CO2 levels between a low of 600 ppm and a high of 1200 ppm, more CO2 will be 'eaten' from the air by the plants as they will not get 'lazy' by synthesizing less RUBISCO enzymes. Turn on CO2 injection at 600 ppm, turn it off at 1200 ppm, and then let the crop suck the CO2 back down to 600 ppm before injecting more.

    The fastest growth by plants happens when they have unlimited water at their roots, and when the VPD is highest (ie 35-45% RH), combined with high light levels (ie PFD or photon flux density) at 1500-1800 umol (like the sun!), and they have dynamically enriched CO2 levels.

    Combine this with ideal air temperature (75 Deg F) and balanced mineral nutrients, and the plants transpire like crazy, fix CO2 like mad as light drives the 'engine' of photosynthesis at full speed, and you get maximum yield.
    DirtyEyeball696 likes this.

    DirtyEyeball696 Well-Known Member

    I have 12- 1000 watt lights & 2 aprilaire 95 pint a day dehumidifiers in a 20x20' room. What would be an optimal temperature to run co2 in your opinion. I have a hydrogen co2 generator so it's watercooled.

    Kush Is My Cologne

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