High temp for maxed out co2 effect, but how much is too much for roots?

[siftedunity]

I go a step further and use low and dry throughout flower. It drastically reduces stretch, grows physically smaller flowers with much higher trichome density.

When I think of hot/wet flowering environments, I think of the amazon where all the plant structures are 'oversized' compared to more moderate climates. Nowhere near as trichome dense as the opposite end of the scale.

you shouldn't have to sacrifice good yields for more quality. on the other hand ive grown cool and dry when ive had not choice at the time. they under perform in general.

 

[Douglas.Curtis]

you shouldn't have to sacrifice good yields for more quality.

I don't see vegging longer as a sacrifice, not after sampling the end product. The issue is, everyone in the industry has been approaching yields from a low quality stand point. Obviously the average watt/hours per harvest will go up as higher quality becomes the focus. Granted, this is for smoking quality.

 

[RockinRobot]

I don't see vegging longer as a sacrifice, not after sampling the end product. The issue is, everyone in the industry has been approaching yields from a low quality stand point. Obviously the average watt/hours per harvest will go up as higher quality becomes the focus. Granted, this is for smoking quality.

I disagree completely. Growing with CO2 won't reduce quality. You don't run CO2 and high temps the entire grow. The vast majority of resin production is done during ripening when we don't run CO2 anyway. I grow for personal use not for commercial and my buds are always frosty and tasty. Absolutely no difference in quality from my days growing without CO2. Just 30% more quantity.

I will agree that many commercial growers will over use CO2, but when used correctly it won't reduce quality.

 

[Douglas.Curtis]

I grow for trichome density, and as far as I'm aware, anything above about 800ppm affects quality. Larger leaves, longer stems, bigger flowers, higher yield. Low and dry, we're talking the same number of trichomes per plant, on a much smaller surface area than you're used to. More resin to plant content, no explosion of growth in stretch, no massive flowers.

The terpene retention and the difference in smoking quality is stunning, and I particularly like the "single-stem" aspect of the flowers.

I can safely say **most** people/growers have never experienced trichome dense cannabis. It runs counter to 90% or more of the 'growing info' on the net.

 

[RockinRobot]

I grow for trichome density, and as far as I'm aware, anything above about 800ppm affects quality. Larger leaves, longer stems, bigger flowers, higher yield. Low and dry, we're talking the same number of trichomes per plant, on a much smaller surface area than you're used to. More resin to plant content, no explosion of growth in stretch, no massive flowers.

The terpene retention and the difference in smoking quality is stunning, and I particularly like the "single-stem" aspect of the flowers.

I can safely say **most** people/growers have never experienced trichome dense cannabis. It runs counter to 90% or more of the 'growing info' on the net.

These plants are at 38 days when picture was taken. Even my large fan leaves already have frost. This is with full CO2 and heat. They will frost up even more once they reach the last 3 weeks when there's no CO2 running. This isn't even great genetics. This is an 11 week strain so I'll shut down CO2 in another 1-2 weeks

So again I have to disagree with you.

 

[Douglas.Curtis]

Nice looking plants. I stand by my statements.

 

[St. Phatty]

How much CO2 is too much, for Cannabis ?

Or maybe a better question would be - at what point does CO2 augmentation hit diminishing returns ?


If CO2 levels got too high for Cannabis to grow ... that would be a problem.

 

[bsgospel]

For C3 plants ~1200 ppm @ ~85-95 degrees and 60-80% rh, assuming perfect light. Above that it costs the plant more in energy to achieve less.

 

[Lost in a SOG]

In normal grow rooms running decent ppfd and mediums Co2 will be the limiting factor holding back growth.

Once co2 is no longer the limiting factor something/s else, within most circumstances, will become the thing limiting growth.

Often nutrients as the plant eats more to build the biomass, but can be light/air movement/water availability.. So you have to keep these other growth factors around the sweet spot.. also as mentioned there is no point in adding above atmospheric after the flowers have set.

 

[popta]

You need pretty high ppfd for 1200 ppm of CO2, not just "decent". Supposed to have something around 1000 ppfd to match that much CO2. 600w users need not apply, that's 1000w lights less than two feet from the plant (and never more than 4 feet apart) territory.

 

[RockinRobot]

How much CO2 is too much, for Cannabis ?

Or maybe a better question would be - at what point does CO2 augmentation hit diminishing returns ?


If CO2 levels got too high for Cannabis to grow ... that would be a problem.

Too much CO2 can actually cause issues. I'm only running 600w HPS and I tend to get deficiency issues above 1000ppm. Under a 1000w I think 1200ppm is about the max that's beneficial. I've heard of people running at 1500ppm but IMO that's to high.

Remember to match your feed ppm to CO2 ppm.

I also run dry and don't follow proper VPD. According to VPD I should be around 80% RH at 85° but I run closer to 50% 60% max.

As someone said plants have 3 main limiting factors, Light, Nutrients and CO2. Adding CO2 to a grow with 150w HPS, for instance, would probably do nothing due to light being the limiting factor.

 

[Lost in a SOG]

Anyone running co2 should really have a PAR meter and factor that in to everything they do.

Top LEDs easily match 1000s in PAR.. and without the daft stretch..

 

[dank.frank]

Great conversation taking place here.

I go a step further and use low and dry throughout flower.

Years ago, Backyardfarmer convinced me to try higher humidity - 60%+ - in early flower, and doing so does make a big difference in growth rates.

Around week 4 I'll get humidity back around the 40-45% range. End of flower my rooms are always 28-35%.

Plants grown with CO2 enrichment produce less trichome dense flowers than those grown without? Evidence?

I thought lowering humidity and temp along with reducing light cycle near the end were all commonplace practices for increasing density... hell, I think I recall GH recommending last two weeks of flower to run an 8/16 cycle to maximize resin on WW.

My statement is not that CO2 reduces trich production. My argument is that temperatures higher than 78, at all, reduces trich production. With or without CO2.

I've never screwed around with lighting cycle. I've certainly not tried to start revegging them during the last weeks of flower!

This is an 11 week strain so I'll shut down CO2 in another 1-2 weeks

Too much CO2 can actually cause issues. I'm only running 600w HPS and I tend to get deficiency issues above 1000ppm. Under a 1000w I think 1200ppm is about the max that's beneficial. I've heard of people running at 1500ppm but IMO that's to high.

I've always suggested on at 900 and off at 1100, regardless of lighting.

So you have to keep these other growth factors around the sweet spot.. also as mentioned there is no point in adding above atmospheric after the flowers have set.

Bingo. All things have to be kept in balance.


---------------

Now, I'm curious though. Why do you guys shut the burner or tank off at a certain point in flower. I've run CO2 burners before but always kept it on. In part, because the room wasn't all at the same stage of growth. Which, is the same scenario that Phillthy had in his room, except he ran 1500 non stop, I'm fairly certain. You could get light headed in his room in about 8-10 minutes. It was sealed tight.

Something he and I used to discuss though were the differences between our flowers, given we grew many of the same cuts. When I wasn't running Co2, my flowers always had more flavor. ALWAYS. His flowers were always more potent. ALWAYS.

I'm wondering now, if the constant addition of CO2 is what is most responsible for the difference in flavor between our flowers, and perhaps not so much that we used a different base soil mix. We used the same amendment recipes, but the base soil was different.



dank.Frank

 

[RockinRobot]

Dank_frank

Main reason for stopping CO2 is it will slow ripening due to causing high ethylene levels. .

I have run end to end CO2 in the past because of perpetual grow. Flowers would tend to start foxtailing near the end.

 

[PDX Dopesmoker]

Theres definitely a sweet spot for root zone temperature which is a different temperature from the air temperature. I've never seen anyone on a cannabis site doing too much with the idea, but theres academics in other areas of agriculture who've looked into the topic.

 

[Shmavis]

Great conversation taking place here.



Years ago, Backyardfarmer convinced me to try higher humidity - 60%+ - in early flower, and doing so does make a big difference in growth rates.

Around week 4 I'll get humidity back around the 40-45% range. End of flower my rooms are always 28-35%.



My statement is not that CO2 reduces trich production. My argument is that temperatures higher than 78, at all, reduces trich production. With or without CO2.

I've never screwed around with lighting cycle. I've certainly not tried to start revegging them during the last weeks of flower!





I've always suggested on at 900 and off at 1100, regardless of lighting.




Bingo. All things have to be kept in balance.


---------------

Now, I'm curious though. Why do you guys shut the burner or tank off at a certain point in flower. I've run CO2 burners before but always kept it on. In part, because the room wasn't all at the same stage of growth. Which, is the same scenario that Phillthy had in his room, except he ran 1500 non stop, I'm fairly certain. You could get light headed in his room in about 8-10 minutes. It was sealed tight.

Something he and I used to discuss though were the differences between our flowers, given we grew many of the same cuts. When I wasn't running Co2, my flowers always had more flavor. ALWAYS. His flowers were always more potent. ALWAYS.

I'm wondering now, if the constant addition of CO2 is what is most responsible for the difference in flavor between our flowers, and perhaps not so much that we used a different base soil mix. We used the same amendment recipes, but the base soil was different.



dank.Frank

It’s more a claim being made by Douglas, than you. (Should’ve quoted him). But I am curious, why would you think above 78º leads to a reduction of trichome production? Does this apply to outdoor plants as well?

If temps aren’t raised when running CO2 another limiting factor is introduced. Full benefit of gassing goes unachieved at a lower temp, which cannot facilitate full utilization, as I understand it.

A light cycle of 8hrs on, 16hrs off, will not reveg a plant - not only not in the last weeks of flowering, but probably never. Found the recommendation: “Greenhouse suggests changing the lighting to 8 hours during the last 2 weeks of flowering in order to halt regrowth of the buds and produce just enough stress to coax out the maximum amount of sticky resin per inch.” (For White Widow). Even when I grew WW I didn't go 8/16, but I do regularly go 10/14.

 

[RockinRobot]

These pictures are at 54 days. CO2 was shut off 2 days ago. I guess it didn't hurt the trichome density and they aren't done ripening.

 

[Mountain Wizard]

Great info guys, thx for all the input!

 

[Mountain Wizard]

Thx for all the information guys, good discussion!

 

[Douglas.Curtis]

These pictures are at 54 days. CO2 was shut off 2 days ago. I guess it didn't hurt the trichome density and they aren't done ripening.

What's with all the green? That's not trichome dense. hehehehe