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

FarmerWilly · Mar 26, 2019

For first 2-4 weeks it is recommended to keep temp as high as 30-35C for maximum co2 benefit.

I'm worried about too high root temp in this case. At this stage my plants doesn't cover all that crop area yet and heat penetrates into the roots more easily. It's a coco grow to keep in mind. If roots would be in hydro system, it would be more easy to keep rootzone cooler, but in my coco it measures as high as 26-28C inside the pot (actual rootzone) when there is about 33C everywhere around.

One trick would be to water many times a day with cool water (around 18C maybe), but..

Does anyone know what to do in this case? What is a good rootzone temp when gassing with co2 with high temps?

troutman · Mar 26, 2019

Don't try to max things out. You're going to stress your plants and yourself out. :tiphat:

RockinRobot · Mar 26, 2019

Watering more often to try and keep root temps lower would most likely result in root rot. You will have to pay more attention to when and how much you water. You're going to want to let them dry without over drying.

I run flood and drain in hydroton with room temps around 85-88f and have gotten root rot thinking more frequent watering would help root temps.

You can insulate your pots with thin reflective insulation and cover the tops with it as well to help keep heat from the roots.

dank.frank · Mar 26, 2019

C02 and high temps is a waste of time. You aren't growing a crop for it's vegetative production, you're growing a crop for it's resin glands.

Keep temps below 78 even with Co2 and you'll find yourself growing much better cannabis.

dank.Frank

RockinRobot · Mar 26, 2019

dank.frank said:
C02 and high temps is a waste of time. You aren't growing a crop for it's vegetative production, you're growing a crop for it's resin glands.

Keep temps below 78 even with Co2 and you'll find yourself growing much better cannabis.

dank.Frank

Sorry to dissagre.

You're wasting CO2 if you don't raise temps. The reason for raising temps is to cause the plants to transpire more allowing them to eat more. Most terpene and resin production occurs near the end of flower when CO2 is not running anyway.

Lost in a SOG · Mar 26, 2019

There's always a trade off somewhere.

Df is saying youre sacrificing quality for yield by doing that.. id have to agree with him ime.

Ive never seen a benefit in going to those temps with co2. Also ime plants dont want co2 in the final weeks..

Co2 closes stomata lowering transpiration so its common to lower RH below ideal vpd to account for this but i wouldnt like to cook em as well.

Regardless you want to keep roots around or below 20..

popta · Mar 26, 2019

30C/85F is enough, I've never personally seen anything that shows 35C is beneficial. Either way though, are you actually losing plants to pythium?

If yes: reduce root zone temps

If no: why are we wasting time fear mongering?

Whatever a number is it's only a problem if it's a problem. Look at the plants and they'll tell you what to do.

FarmerWilly · Mar 26, 2019

RockinRobot said:
Watering more often to try and keep root temps lower would most likely result in root rot. You will have to pay more attention to when and how much you water. You're going to want to let them dry without over drying.

I run flood and drain in hydroton with room temps around 85-88f and have gotten root rot thinking more frequent watering would help root temps.

You can insulate your pots with thin reflective insulation and cover the tops with it as well to help keep heat from the roots.

Please read this sticky thread about growing in coco:

It's quite the opposite of what you are saying. Let me quote few lines:

"[FONT=Arial, Helvetica, sans-serif]When dialing the watering schedule it's important to take into consideration the size of pot that your using and the size of your root mass, for example if you pot up some freshly rooted clones into 6.5Ltr pots and start watering them 3x per day you will run into some problems. People like to say that you can't overwater in coco, I agree with them to a certain extent but you can overwater if you give them too much when they don't have a well developed root system, that's why it's important to harden off the roots and let 'em go hunting for nutrients at the beginning, this will help to build the root system. When I pot up a freshly rooted cut I let it have wet-dry cycles for a few days then I slowly up my watering, at the end of week one I'm watering once per day, I aim to be watering 3x per day by the end of week 2. Once the root system is developed it is very very hard to overwater, they will take all you can throw at 'em and ask for more."[/FONT]

FarmerWilly · Mar 26, 2019

Here's the thread: https://www.icmag.com/ic/showthread.php?t=241341

FarmerWilly · Mar 26, 2019

troutman said:
Don't try to max things out. You're going to stress your plants and yourself out.

I don't know about stressing myself out, but stress might actually be a good thing overall. Think about stressing yourself out in the gym for example. It pays off in the end if done correctly. At first it's painful and uncomfortable, but you get stronger and you will feel better in the end. But plants? Doesn't trichome production have something to do with stressing the plant?

I get it what you're saying, but there is also an other side to these words.

Last time I got 1.8gpw. This time I got 1.6gpw - was it because I lowered temps in the end or was it because of something else, I don't know, but I did not actually recognize an increase of quality to be honest, only the decrease of mass. So there's that.

One day I will have lots of different rooms to do science with. I will be able to compare results side by side, but until then I will lay my questions here. Don't tell me to not bother and let the plants do their thing, okay? :tiphat:

FarmerWilly · Mar 27, 2019

dank.frank said:
C02 and high temps is a waste of time. You aren't growing a crop for it's vegetative production, you're growing a crop for it's resin glands.

Keep temps below 78 even with Co2 and you'll find yourself growing much better cannabis.

dank.Frank

You got it completely wrong in my opinion. It matters big time if you're a big grower interested in optimization of costs and high production, because shorter vegging time can save you a lot of effort per year. Do the math yourself.

Well, you can just veg for longer period of time before moving into flowering room, but just so you know, plants can grow a lot in first few weeks of flowering if gassing with co2 combined with high temps. Very possible that they don't even need a seperate vegging room at all. Clones rooted > clones going into flowering. This is what I do, because I'm tired of that excessive leaf mass.

If you grow in a tent, then it might not matter much, but if you would own an industry, you would think again about that time being wasted.

When exactly should temperature be lowered and to what extent is a completely different story imo and I'm very interested to get to know more about it. Feel free to share your knowledge.

I have seen with my own eyes what co2 is capable of and it literally blew my mind. I can't say that my finished product got shitty after starting to use co2 with higher temps. Not at all.

smilley · Mar 27, 2019

You could put coils of copper tubing in your pots and circulate cool water through them to keep them cool. co2 is way out of my league but if your running flood and drain it should be easy to cool the roots. Insulation at the top of the pots would help a lot too.

dank.frank · Mar 27, 2019

When you say you noticed no difference in quality, only a reduction in size, I have to wonder. You use a scale to make one assessment, what testing methodology did you use to REALLY determine "quality" outside of a subjective metric - perception.

Not trying to be difficult but only to make a point. If you were pressing entire harvest into rosin or making extract you'd have a % of return based on a measured weight of flower input. That is a valid metric to quantify quality because it directly relates to resin content produced.

You talk as if science matters then you use anecdotal qualifiers.

I'm not saying C02 is a waste. I'm saying running higher temps in conjunction with C02 results in lesser quality flowers, and therefore is a waste. But that is also subjective, based on what your end goals are. Volume of output or quality of output.

Proof is in the pudding. Look at Phillthy's old thread.

It's my personal experience, and that of the best growers I've ever met, following VPD does not result in the highest trichome field density possible. Make of it what you will.

dank.Frank

FarmerWilly · Mar 27, 2019

I'll keep it in mind. Thanks.

FarmerWilly · Mar 27, 2019

This is the plan I have come up with at the moment. I will be probably changing it many times before reaching the sweet spot. Being able to do side by side comparisons is my goal. Soon.

Lost in a SOG · Mar 27, 2019

Imo

Extra heat = higher transpiration = more stem weight.. not more quality resinous flowers. Just my opinion.. i think people forget how much stems weigh and how much that factors in to things..

Even bud thc tests..

Douglas.Curtis · Mar 27, 2019

dank.frank said:
It's my personal experience, and that of the best growers I've ever met, following VPD does not result in the highest trichome field density possible. Make of it what you will.

dank.Frank

Thank you, I completely agree.

Grow for the product you want. If you want the maximum harvest weight possible, go hot, wet and use lots of CO2.

Looking for maximum resin weight at harvest? Veg longer, grow cooler and grow drier. All those VPD charts floating around the net? My temp/rh range for flowering is nowhere on them.

Wendull C. · Mar 27, 2019

Has anyone else noticed dropping the humidity drastically at the end of flower creates much more resin?

Best I could find was Kevin Jodrey saying resin acted as an anti desiccant to protect the flowers. I have heard no one else discuss this.

Shmavis · Mar 28, 2019

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.

Douglas.Curtis · Mar 28, 2019

Wendull C. said:
Has anyone else noticed dropping the humidity drastically at the end of flower creates much more resin?

Best I could find was Kevin Jodrey saying resin acted as an anti desiccant to protect the flowers. I have heard no one else discuss this.

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.

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

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