Why can temps be higher growing outdoors vs indoor

J Bleezy said:

I think it's a pretty good guess of one of the reasons as it would be preety tough for them to deplete the earth of co2.
Since you've argued against my comments for days now, care to offer your opinion on why plants can handle more heat outdoors?

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To deplete a room of CO2, we must assume that room has very little or no ventilation. Even an 8x10 closet with a small 50CFM fan would replace the air 12 times an hour. I would venture a guess that the indoor plants haven't been hardened off like most outdoor plants require. Soil temp also sounds like a viable theory as I seem to recall 76°+ soil temps can halt growth and inhibit beneficial bacteria growing in the soil.
I posed this question to my old Greenhouse Management professor this morning. We'll see what he has to say.

Actually, now that I have had a sober morning to think about it, I would attribute the heat tolerance to the plants being hardened off. Almost all plants that are started indoors need a hardening off period before they can be put outdoors. Just so they kind of get used to the weather extremes and what not.

Okay so, soil temp and hardening off.
Try running rdwc with your water chiller set to 65 and let your temps get up to 105f WITHOUT ventilation and without replacing co2 and let me know how that works out for you.
Hardening off is just ridiculous. I almost don't know how to respond to that. So you're saying that if I slowly bring my temps up indoors, then I can pretty much put my temp wherever and the plants won't mind?

I haven't read any of this, little drunk at work.

I will say this tho... Convection vs. conduction

J Bleezy said:

Okay so, soil temp and hardening off.
Try running rdwc with your water chiller set to 65 and let your temps get up to 105f WITHOUT ventilation and without replacing co2 and let me know how that works out for you.
Hardening off is just ridiculous. I almost don't know how to respond to that. So you're saying that if I slowly bring my temps up indoors, then I can pretty much put my temp wherever and the plants won't mind?

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Without ventilation? Where did that even come into the equation? Have you ever worked in a commercial greenhouse? I have. For 4 years while earning my degree in Horticultural Sciences.
I'm not saying you can bring temps slowly to 105 and keep them there. You said that. I am saying that after a hardening off period in which the plants are put in a semi-sunny area outside they become acclimated to the environment and can then be put in full sun with fewer problems. This should be common knowledge. You act as though you've never heard of it.
I never said that plants don't use CO2, they do. I even gave the formula for photosynthesis. Why are you assuming that there is no ventilation? Nobody said that but you.

Well, lets see. Because ventilation brings in fresh co2, which you already DID say in not part of the equation here (and now you are trying to backpedal on, but I won't let you do that). So, if the temp is gonna be 105f no matter what, then why else would you want ventilation? Oh I know! Because of that thing that you said doesn't matter in this situation, co2!
And yes, you did say harden them off for indoors

P.S.
I don't give a rats ass about your greenhouse work or "degree in horticulture sciences", which might I add every other person on these forums claim they have.
Fact is, I said co2 is a big reason why and you argued with me for days and now you're trying to act like co2 actually is one of the reasons here. Then why in the hell have you been quoting me for 3 days arguing with every one of my comments?

J Bleezy said:

Well, lets see. Because ventilation brings in fresh co2, which you already DID say in not part of the equation here (and now you are trying to backpedal on, but I won't let you do that). So, if the temp is gonna be 105f no matter what, then why else would you want ventilation? Oh I know! Because of that thing that you said doesn't matter in this situation, co2!
And yes, you did say harden them off for indoors

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Dude, I said repeatedly that with proper ventilation CO2 won't be a problem. You produced 1 weak blog post some stoner wrote about a closet. CO2 levels aren't going to drop that dramatically, even with minimal ventilation. Can you please Google "hardening off " and then respond? It is the process of acclimating your plants to the extreme swings that nature can give. Might be 50 at night then 90 the next day etc.. If you were to give your plants an artificial hardening off, they probably would tolerate higher temps. It probably wouldn't be ideal, but in theory it should work. Indoor temps are so easily manipulated it's just recommended to keep them in a narrower range than what mother nature does.
I can't find a single post where I said plants don't use CO2. They do, but depletion is not a major contributing factor in this case.

J Bleezy said:

P.S.
I don't give a rats ass about your greenhouse work or "degree in horticulture sciences", which might I add every other person on these forums claim they have.
Fact is, I said co2 is a big reason why and you argued with me for days and now you're trying to act like co2 actually is one of the reasons here. Then why in the hell have you been quoting me for 3 days arguing with every one of my comments?

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Good day, Sir.

No, you didn't "say" plants don't use co2, you've tirelessly argued against my comment that said plant can and will use a rooms co2 supply up.
And now you're saying proper ventilation is key.
Well, buddy I hate to break it to you(maybe they didn't teach you this in horticulture science),most rooms that get up to 105f DON'T have good ventilation, hence the reason they are 105f.
And you want to talk trash about my "one blog post" that was actually taken from a dr who article, then please by all means post at least one single link that refutes what I am saying and I'll go find something more official for you.
Until then, you're still just an internet know it all in my book
Peace boss

J Bleezy said:

No, you didn't "say" plants don't use co2, you've tirelessly argued against my comment that said plant can and will use a rooms co2 supply up.
And now you're saying proper ventilation is key.
Well, buddy I hate to break it to you(maybe they didn't teach you this in horticulture science),most rooms that get up to 105f DON'T have good ventilation, hence the reason they are 105f.
And you want to talk trash about my "one blog post" that was actually taken from a dr who article, then please by all means post at least one single link that refutes what I am saying and I'll go find something more official for you.
Until then, you're still just an internet know it all in my book
Peace boss

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I said Good day, Sir.

Hot temps during vegetative growth through the first few weeks of flower are fine, but 85+ temps during the ripening stage = regs.

You two really turned this into a pissing match. People earlier hit it in the bullseye. Dig down a foot into the earth outside. You'll immediately feel the difference in temps. That temp is consistent...that's the key. 105 air temperature outside does not correlate with increased temp temps in the soil a foot or more down. Put the roots in a pot above the ground and you will have a root zone that will take only a few hours of 105 to become inhospitable. CO2 has nothing to do with this.

I'm sorry if this offends, but from what I remember from reading somewhere regarding adding CO2 to grow to do anygood for plants they had to be in sealed pressure controled room's and the amount of CO2 would be toxic

Another answer could be that although the outside temps get hot, the soil in the ground remains the proper temperature for the root zone. Indoors, however, the room gets hot and so do the roots which invites root rot and mold.

Craig1969SS said:

You two really turned this into a pissing match. People earlier hit it in the bullseye. Dig down a foot into the earth outside. You'll immediately feel the difference in temps. That temp is consistent...that's the key. 105 air temperature outside does not correlate with increased temp temps in the soil a foot or more down. Put the roots in a pot above the ground and you will have a root zone that will take only a few hours of 105 to become inhospitable. CO2 has nothing to do with this.

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Lol people grow in smart pots above the ground outdoors all the time champ, including me....

Actually most people who know what they're doing put outdoor plants in smart pots above the ground

The ground keeps the root zone cool. If you can keep you pots and roots cool you can run higher temps indoors to.

Opposite hold true for cool weather. The ground keeps the roots warm. That's why they can handle cold weather and even a frost or two.