when is cold too cold?

Greedy-Green said:

I'm no expert but Id say at 50 you have to add less moisture to the air/grow room to get a 1% increase than you would at 70? But at 70 the air can hold more moisture so it should be easier to raise the humidity? And I'm guessing it's the same princable for lowering humidity?

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Don't forget, water is liquid state. Humidity is vapor form. Just because there's more water, doesn't mean there's more vapor by volume.

Greedy-Green said:

Be


That makes sence because the air can hold more moisture it takes a higher amount to increase percentage, I suppose u could say 50 is a 500ml bottle and 70 is a 750ml bottle is will take more to fill the 750ml to half way then it will to fill the 500half way?

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Interesting way of looking at it. You turned temp into volume as a comparison.

It you had 2 500ml bottles and put 2 drops if water in each and then placed one in a 50 degree room and the other in a 70 degree room, the one in the 50 degree room would retain more liquid state by volume if both the RH were at 50%.

Connoisseurus Rex said:

No, that's not what I'm thinking at all. I'm thinking that a colder air is a denser air, which means restricted movement of molecules over any given volume. That just happens to mean that a colder air can hold more water, oxygen, and CO2 molecules by volume than a warmer air by volume. Ask any drag racer about cooler, denser air.

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The air won't be any denser. In a seal system that thinking may work, but the system in question would have to be totally air tight. The density of the air will match that of the air outside because of the laws of physics. Lower density = lower pressure, higher pressure will move to equalize the pressure and along with it the density. You have a decent supply of knowledge, but application of that knowledge is haphazard.

nomofatum said:

The air won't be any denser. In a seal system that thinking may work, but the system in question would have to be totally air tight. The density of the air will match that of the air outside because of the laws of physics. Lower density = lower pressure, higher pressure will move to equalize the pressure and along with it the density. You have a decent supply of knowledge, but application of that knowledge is haphazard.

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The air outside the tent is colder than the air inside the tent. Air outside the tent is in the low 40s during the day and sometimes as low as the high 30s at night. It's drawing in even more dense air. I didn't tell you that, so I'll give you the benefit of the doubt.

Look man, I'm not trying to change growing or anything. Other people do this too. I didn't invent it, it's not any better or worse... It just works. I have normal growth. Nothing suffers. I'm just saying that if somebody has to grow cold and is worried about it... This is how you can do it wit thou hurting your plants.

I realize how important temps are to you folks. I can agree. Makes growing much easier for your application. I don't have that luxury. I have to grow in the cold. So instead of not growing, or fighting to keep temps up, I just learned how to make cold temps insignificant. Nothing special.

That's also the reason I'm liking the 6/2 schedule. It doesn't cool down as much with only 2 hrs of off time between lights on.

Connoisseurus Rex said:

That's also the reason I'm liking the 6/2 schedule. It doesn't cool down as much with only 2 hrs of off time between lights on.

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The 6/2 thing, veg only or is it actually working for flower? If it works for flower it would be quite interesting as a countermeasure against cops looking for the cycle.

This thread........

So I spent about 5 seconds putting "temperature vs rate of photosynthesis" into google images....

Rex's suggestion that "it's the same" is ridiculous. Rex needs more ridicule...


http://www.tutorvista.com/content/biology/biology-ii/nutrition/factors-affecting-photosynthesis.php


http://www.docbrown.info/ebiology/photosynthesis.htm


http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_21c/life_processes/plantfoodrev5.shtml


http://fhs-bio-wiki.pbworks.com/w/page/12145771/Factors effecting the rate of photosynthesis


http://biology-igcse.weebly.com/effect-of-temperature-on-the-rate-of-photosynthesis.html


http://www.plant.uoguelph.ca/research/homepages/ttollena/research/cropheatunits.html

Rex should really learn when to quit. Noobs often can't distinguish between bullshit and experience. Please quit it with the bullshit.

Edited: Replaced all occurrences of "OP" with rex. I thought OP was rex.

nomofatum said:

The 6/2 thing, veg only or is it actually working for flower? If it works for flower it would be quite interesting as a countermeasure against cops looking for the cycle.

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I doubt they'll flower. This is just for veg. There's a theory that plants can only process 6 hrs of light at a time. I've checked the difference in root mass from 18/6 to 24 hrs. 24 had more root fiber mass in my trials. Not necessarily bigger roots, but definitely more fibers and mass.

So I figured I would see how they operate when given 6hrs of light and then a break. Some people say they won't "sleep" after 2 hrs of off. I don't see what that has to do with it, but whatever. Root mass is achieved via turgidity. That can be up for debate.

Anyhow, if 24hrs show more root mass, hypothetically they could be stressing if they can only process 6hrs of light. 18/6 may be too much darkness, maybe even 20/4. I dunno. That's why I'm testing. So far, it doesn't seem any different to me.

Plant recovery is going to be another test. Just to see if there's any difference at all.

ssadf adsfasdf said:

Surprised no one mentioned genetics. An Indica afgan mountain strain would be less effected by cold then lets say a mexican sativa. That being said i have found that all the plants i have grown have done much better in the 75 F range. Just my two cents

Peace

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Maybe. I've had pure indica's grow and flower in 100 degree weather and pure sativa's handle multiple hard frost in the 20's.

I personally like my bud to get hit with cold weather. Most everything I've grown outdoors loved cool temps in flower.

churchhaze said:

So I spent about 5 seconds putting "temperature vs rate of photosynthesis" into google images....

OP's suggestion that "it's the same" is ridiculous. OP needs more ridicule...

http://www.tutorvista.com/content/biology/biology-ii/nutrition/factors-affecting-photosynthesis.php

http://www.docbrown.info/ebiology/photosynthesis.htm

http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_21c/life_processes/plantfoodrev5.shtml

http://fhs-bio-wiki.pbworks.com/w/page/12145771/Factors effecting the rate of photosynthesis

http://biology-igcse.weebly.com/effect-of-temperature-on-the-rate-of-photosynthesis.html

http://www.plant.uoguelph.ca/research/homepages/ttollena/research/cropheatunits.html

OP should really learn when to quit. Noobs often can't distinguish between bullshit and experience. Please quit it with the bullshit.

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Perhaps you should have read the entire thread. I explained why temp APPEARS to affect photosynthesis. It's not even part of the photosynthesis process...

Connoisseurus Rex said:

Perhaps you should have read the entire thread. I explained why temp APPEARS to affect photosynthesis. It's not even part of the photosynthesis process...

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Perhaps you should learn when to quit.

churchhaze said:

It appears to affect photosynthesis because it does affect photosynthesis...

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Ugh... I'm not going to argue with you. Go back and reread the thread. Or look up what the photo in photosynthesis means... And then remember what accompanies light.

Connoisseurus Rex said:

Look man, I'm not trying to change growing or anything. Other people do this too. I didn't invent it, it's not any better or worse... It just works. I have normal growth. Nothing suffers. I'm just saying that if somebody has to grow cold and is worried about it... This is how you can do it wit thou hurting your plants.

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You can't say it's no better or worse unless you test it, side by side preferably. The plants will adapt to some extent, but cooler temps are going to slow down the chemistry in the plant.

If all other variables are left the same and you only increase temp closer to optimal, yields will also increase closer to optimal.

There is plenty of evidence to close the book on cool temps being able to match the results of more optimal temps. The interesting place to look at cooler temps would be the resulting taste differences. At too high of temps taste gets horrible. Often fruits/vegetables get sweeter and tastier if left to go until temps get lower, I might believe that taste could be better on some plants in cooler temps, but you can't fight the laws of physics on growth rates in different temps.

Connoisseurus Rex said:

Perhaps you should have read the entire thread. I explained why temp APPEARS to affect photosynthesis. It's not even part of the photosynthesis process...

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Lol, temps aren't part of they photosynthesis process? Really? So photosynthesis can occur at the same rate regardless of temp? Sorry, you do realize temp is actually the measure of how fast particles are moving right? The faster they move the faster they can react with each other. This is exactly what happens in any and all chemical reactions, including the vast number of reactions that we call "growth". Colder literally means everything moves slower.

nomofatum said:

You can't say it's no better or worse unless you test it, side by side preferably. The plants will adapt to some extent, but cooler temps are going to slow down the chemistry in the plant.

If all other variables are left the same and you only increase temp closer to optimal, yields will also increase closer to optimal.

There is plenty of evidence to close the book on cool temps being able to match the results of more optimal temps. The interesting place to look at cooler temps would be the resulting taste differences. At too high of temps taste gets horrible. Often fruits/vegetables get sweeter and tastier if left to go until temps get lower, I might believe that taste could be better on some plants in cooler temps, but you can't fight the laws of physics on growth rates in different temps.

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I will test it further. Right now I'm in the lighting experiment. I have grown in the 70s and 80s temp ranges. To me, I see no difference at all.

When the lighting experiment matures , I'll fire up the other tent and take clones to do a side by side.

However, you can't increase temp values without changing the other dynamics to make it optimum for each temp range. You wouldn't run the same humidity for both temps because it's not optimum. That's where the difference lies.

I understand that 50% humidity is 50% humidity, no matter the temp. What you are looking for is how much more moisture you need to put into that air per volume, to get the humidity you desire.

No replacement for displacement.

nomofatum said:

Lol, temps aren't part of they photosynthesis process? Really? So photosynthesis can occur at the same rate regardless of temp? Sorry, you do realize temp is actually the measure of how fast particles are moving right? The faster they move the faster they can react with each other. This is exactly what happens in any and all chemical reactions, including the vast number of reactions that we call "growth". Colder literally means everything moves slower.

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Your assuming the canopy is unaffected by the temp of the light. Photosynthesis takes place in the canopy, not the roots or the air around the canopy, but in the foliage itself.

Connoisseurus Rex said:

Your assuming the canopy is unaffected by the temp of the light. Photosynthesis takes place in the canopy, not the roots or the air around the canopy, but in the plant itself.

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Please be more direct and say "The temperature of the canopy affects the rate of photosynthesis".

That's correct... The temperature of the canopy affects the rate of photosynthesis!! Good work!

It took you a while to come around, but I knew you'd make it!

Connoisseurus Rex said:

I will test it further. Right now I'm in the lighting experiment. I have grown in the 70s and 80s temp ranges. To me, I see no difference at all.

When the lighting experiment matures , I'll fire up the other tent and take clones to do a side by side.

However, you can't increase temp values without changing the other dynamics to make it optimum for each temp range. You wouldn't run the same humidity for both temps because it's not optimum. That's where the difference lies.

I understand that 50% humidity is 50% humidity, no matter the temp. What you are looking for is how much more moisture you need to put into that air per volume, to get the humidity you desire.

No replacement for displacement.

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Yes, it will be difficult to keep the other variable the same with the temp increase, you would likely need a sealed controlled environment. This is why it's important to let yourself learn from others who have the resources to do tests beyond your ability or willingness.