Flower time with CO2 use

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Mugwort

Mugwort

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I’ve been running tank CO2 for this current grow since I flipped them 51/2 wks ago keeping ppms at or around 1500. I’m growing the exact same 3 strains as my last grow which didn’t have CO2. All 3 have 9-11 week flowering times and the first grow was harvested at around 91/2 weeks. These current plants’ buds look as mature at 5 1/2 weeks as the last crop at the time I started the flush at 7 1/2 weeks. The plan was just to start to flush it 7 1/2 weeks. Does CO2 expedite flower maturation as well as size and yield? Do I chance waiting too long by starting my flush at the same time as I did the last crop? The three strains are Chem Dawg, Maui Waui, and Cali Orange. I’m telling you all the growth was malignant with CO2!
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18F055C2 226C 4C6D B12C D9EB411DDFEF
0979AE0C EC87 4AC3 86F4 3F17357EEFB9
 
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Mugwort

Mugwort

366
63
Yes. Your plants had some stress at some point looking at the leaves, which doesn’t help.
Very observant...they did! I went away for a few days and it got too hot in the tent and the CO2 was not on. This was about 3 weeks ago. I turned the lights down to 75% but it wasn’t enough. They seem to have recovered but it was a nasty insult! So your point is that the extra time = more recovery time?
 
Chem77

Chem77

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Very observant...they did! I went away for a few days and it got too hot in the tent and the CO2 was not on. This was about 3 weeks ago. I turned the lights down to 75% but it wasn’t enough. They seem to have recovered but it was a nasty insult! So your point is that the extra time = more recovery time?
My point is stress can cause you to think your bud is finishing earlier than it is, for example hair’s turning brown early. I’m saying my 10 week strain takes the same with or without co2. Might finish a few days earlier but definitely not 2 weeks.
My goal is to keep the hairs white as long as possible. That means big heavy buds when they finally are finished. Consistent environment and stress free is where it’s at. It’s hard to get a flawless run!
 
Mugwort

Mugwort

366
63
My point is stress can cause you to think your bud is finishing earlier than it is, for example hair’s turning brown early. I’m saying my 10 week strain takes the same with or without co2. Might finish a few days earlier but definitely not 2 weeks.
My goal is to keep the hairs white as long as possible. That means big heavy buds when they finally are finished. Consistent environment and stress free is where it’s at. It’s hard to get a flawless run!
Thank you Chem...xlnt advice! I live in the hottest part of the country (Lake Havasu City). The room my tent sits in gets full brunt of the sun so trying to keep a balance between ambient house temperature and the grow room temperature is a choir. I have a big floor fan that blows air in the grow room from the rest of the house. Looks like next summer I’ll need to get a portable ac for that room. I also had 4 vegging plants in a closet that cannot be closed and their lights are on 18/6 so I had to zip tent up. I should’ve turned lights down to 50% while I was gone and left CO2 running. I have two ViparSpectra XS-2000 lights in my 4x4 tent and they are pretty powerful
 
Mugwort

Mugwort

366
63
Thank you Chem...xlnt advice! I live in the hottest part of the country (Lake Havasu City). The room my tent sits in gets full brunt of the sun so trying to keep a balance between ambient house temperature and the grow room temperature is a choir. I have a big floor fan that blows air in the grow room from the rest of the house. Looks like next summer I’ll need to get a portable ac for that room. I also had 4 vegging plants in a closet that cannot be closed and their lights are on 18/6 so I had to zip tent up. I should’ve turned lights down to 50% while I was gone and left CO2 running. I have two ViparSpectra XS-2000 lights in my 4x4 tent and they are pretty powerful
They are still growing white hairs...
 
Chem77

Chem77

292
93
Thank you Chem...xlnt advice! I live in the hottest part of the country (Lake Havasu City). The room my tent sits in gets full brunt of the sun so trying to keep a balance between ambient house temperature and the grow room temperature is a choir. I have a big floor fan that blows air in the grow room from the rest of the house. Looks like next summer I’ll need to get a portable ac for that room. I also had 4 vegging plants in a closet that cannot be closed and their lights are on 18/6 so I had to zip tent up. I should’ve turned lights down to 50% while I was gone and left CO2 running. I have two ViparSpectra XS-2000 lights in my 4x4 tent and they are pretty powerful
I’m in Michigan and found out last winter I need to add heat using LED’s. Lol, so heat it is.
New mini split this spring, with heat. Old one was A/C only. Lung room/veg room.
B5A983AD F29F 49AA 91D5 BAC12CC115EF

Flower room has heated floor for this winter.
3CC6D66D 4FB3 4A9A B5C1 998C4617D5FE
 
Mugwort

Mugwort

366
63
Oh wow...so you’re at the other end of temp spectrum. Do you run your CO2 right up until harvest. I’m reading that some growers turn it off for the last few weeks before they chop because keeping carbon fixation elevated actually inhibits flower maturation resulting in less dense buds. This is only my 5th grow and I seem to have some kind of unwanted drama with all of them...mostly tent temperature control. I’m getting better at it. Had it not been for those unfortunate two days that I had to leave my plants unattended this grow would’ve gone down without a hitch. I appreciate you answering my questions.
 
MichiganHooligan

MichiganHooligan

I just wet my plants...
Supporter
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So I'm going to chime on with a question rather than a response. What evidence, reasoning or opinions do folks have for amplifying Co2 in marijuana growth?

I mean, I get adding Co2 to planted freshwater aquariums if a tank is overstocked with plants and not enough fish to produce enough Co2 for the plants to thrive but this is completely different.

Plants outdoors don't require added Co2 and plants indoors don't require it either. If your HVAC system works correctly it is pulling in air from outdoors and equalizing the amount of Co2 indoors. Just checking on your plants and breathing on them provides more than enough Co2 for a number of plants in a confined area to process for a couple days.

I mean if there are no vents to the tent/housing and there's zero outdoor air coming into the environment then I can kind of get this. There are still plenty of Co2 sources though in that case even if it's air locked in a vault that someone checks on regularly.

So my question is, why supplement Co2? In the average household there is likely more than enough Co2 unless you have a serious grow op going on.
 
Last edited:
Mugwort

Mugwort

366
63
So I'm going to chime on with a question rather than a response. What evidence, reasoning or opinions do folks have for amplifying Co2 in marijuana growth?

I mean, I get adding Co2 to planted freshwater aquariums if a tank is overstocked with plants and not enough fish to produce enough Co2 for the plants to thrive but this is completely different.

Plants outdoors don't require added Co2 and plants indoors don't require it either. If your HVAC system works correctly it is pulling in air from outdoors and equalizing the amount of Co2 indoors. Just checking on your plants and breathing on them provides more than enough Co2 for a number of plants in a confined area to process for a couple days.

I mean if there are no vents to the tent/housing and there's zero outdoor air coming into the environment then I can kind of get this. There are still plenty of Co2 sources though in that case even if it's air locked in a vault that someone checks on regularly.

So my question is, why supplement Co2? In the average household there is likely more than enough Co2 unless you have a serious grow op going on.
You’re talking with a grow newbie but I have a life science background. It’s pretty simple. If you increase the ambient CO2 you increase photosynthesis which results in a higher yield. All organic compounds have a carbon skeleton and plants assimilate their carbon by fixing atmospheric CO2.
6CO2 + 6H2O = C6H12O6 + 6O2
Glucose and Oxygen
Cannabis is able to assimilate the extra CO2 resulting in increased photosynthetic rates. This also depends on having proper lighting and temperatures as well as RH. I don’t think it increases the concentration of the desired cannabinoids but just one’s yield of buds vis-a-vis same plant reared under normal ambient CO2 levels. There does come a point where photosynthesis starts to drop (somewhere over 1500ppm). So, it doesn’t necessarily increase quality but definitely bud quantity and size. But you are right about ambient CO2 being increased just by having a lot of people in the grow environment. Is it worth the trouble and expense for a recreational grower? That depends on the grower. This is my first time using tank CO2. I tried ProCO2 buckets and they just didn’t make that much of a difference. I’m amazed at the difference in volume of yield being able to keep desired levels consistent with compressed carbon dioxide.
 
Chem77

Chem77

292
93
Oh wow...so you’re at the other end of temp spectrum. Do you run your CO2 right up until harvest. I’m reading that some growers turn it off for the last few weeks before they chop because keeping carbon fixation elevated actually inhibits flower maturation resulting in less dense buds. This is only my 5th grow and I seem to have some kind of unwanted drama with all of them...mostly tent temperature control. I’m getting better at it. Had it not been for those unfortunate two days that I had to leave my plants unattended this grow would’ve gone down without a hitch. I appreciate you answering my questions.
I do run it till the end, just lowering the ppm the last week or so. Co2 made a huge difference in my grows, super dense buds all the way to the bottom.
 
MichiganHooligan

MichiganHooligan

I just wet my plants...
Supporter
576
143
You’re talking with a grow newbie but I have a life science background. It’s pretty simple. If you increase the ambient CO2 you increase photosynthesis which results in a higher yield. All organic compounds have a carbon skeleton and plants assimilate their carbon by fixing atmospheric CO2.
6CO2 + 6H2O = C6H12O6 + 6O2
Glucose and Oxygen
Cannabis is able to assimilate the extra CO2 resulting in increased photosynthetic rates. This also depends on having proper lighting and temperatures as well as RH. I don’t think it increases the concentration of the desired cannabinoids but just one’s yield of buds vis-a-vis same plant reared under normal ambient CO2 levels. There does come a point where photosynthesis starts to drop (somewhere over 1500ppm). So, it doesn’t necessarily increase quality but definitely bud quantity and size. But you are right about ambient CO2 being increased just by having a lot of people in the grow environment. Is it worth the trouble and expense for a recreational grower? That depends on the grower. This is my first time using tank CO2. I tried ProCO2 buckets and they just didn’t make that much of a difference. I’m amazed at the difference in volume of yield being able to keep desired levels consistent with compressed carbon dioxide.
How big is your tent?

I have an IT and Horticulture background.
 
Aqua Man

Aqua Man

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So co2 is beneficial for a few reasons. Improving water use, reducing photorespiration, increasing photosynthetic rates and in turn energy from light turned into energy for the plant used for growth.

It's absolutely (if you have the light intensity) beneficial on a % type basis of overall photosynthesis. So a small plant with small leaf surface area is hardly going to benefits from your efforts. As similar a plant in the last few weeks of flowering where photosynthetic rates are very low.

However when we have a plant under 12/12 it allows you to not only give the plant a much but in turn produce much more energy for plant growth increasing overall growth. We see the most impact in this area as the plants are larger now and the total leaf surface are also. So a 20-30% increase becomes a much larger gain than tiny plant a week or 2 into veg and a small total leaf surface area.
 
Aqua Man

Aqua Man

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My credentials are as follows:

I like cannabis

I like learning about cannabis

I like trying to understand how various systems impact other systems related to cannabis.

Oh and most importantly.....

I'm a high-school drop out

(Who loves growing cannabis mind you)

One more tidbit. High co2 can oartially depending on photosynthetic rates have a negative effect on plant growth. Only during photosynthesis though.
 
MichiganHooligan

MichiganHooligan

I just wet my plants...
Supporter
576
143
My credentials are as follows:

I like cannabis

I like learning about cannabis

I like trying to understand how various systems impact other systems related to cannabis.

Oh and most importantly.....

I'm a high-school drop out

(Who loves growing cannabis mind you)

One more tidbit. High co2 can oartially depending on photosynthetic rates have a negative effect on plant growth. Only during photosynthesis though.

Just saying, some of the wealthiest people in the world dropped out of school. I think High minds are different 🤯
 

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