Temperatures, fact or fiction?

[nongreenthumb]

A lot of growers always seem to say that your grow room should be around 85 degrees.

Marijuana grows outdoors and more often than not in a hot climate.

What temperature can it reach up to during summer in california or how about india up in the mountains where kush comes from, or some tropical sativas. I'm pretty damn sure that these plants grow just fine without any human contact in heats in excess of 100 degress.

My grow room right now is currently sitting at around 98 degrees, i'm suffering no burning effects and the plants appear to be healthy.

In order to get decent buds you need a decent amount of lumens or par or whatever term you want to use, surely to get enough from the sun the temps have got to be warm enough.

If you look at some website for seed providers they say some strains are indoors and some strains are outdoors, however the indoor strains can be flowered outdoors providing you live within a specified distance from the equator.

So what is the truth at what temperature does marijuana actually thrive on with enough of the right elements in the other areas such as air and water and food the plant shouldn't worry if its in warmer heats.

What do you guys think?

 

[JohnnyPotSeed1969]

i think it probably depends on where the strain originated from. strains from near the equator probably have a greater tolerance to heat than strains say from northern europe. cannabis grows on every continent except antarctica and the north pole, so i would expect there to be a wide difference in temperature tolerances.

 

[TheConstantGardner]

evaporation -> rise in humidity from high heat possibly?

 

[donnieosmond]

I'm only a newb ngt, and I've always wondered the same thing as my grow room often runs higher than needed. Based on the information I've read so far it seems that your speculation on climate is true. The other thing is that marijuana may grow in high temperatures but it may not flourish. You get what I mean? It's just another factor that effects yield, so I'd suspect that if you had high heat but optimal growth factors in other areas your yield would be pretty nice, just not as nice as it would have been since it seems heat slows down growth to some degree (to what degree I have no idea).

P.S. I found the post I was looking for. Here it is - -

Yeah like cloudflyer said plants regulate small openings, stomata, on leaf undersides to allow CO2 to enter and oxygen to exit.....

Also. Plants have five basic needs. Each one amounts 20 percent of a plants ability to grow to its maximum potential. When all of these needs are met at the maximum, the result is maximum growth (20% x 5= 100%)! If one of the needs arrives at only 15 percent, all growth is impaired equally (15% x 5= 75%). If two or more of the basic need are not met, growth slows quickly. Even with the best hydroponic system money can buy, in a garden where relative-air humidity is 80 percent when it should be about 50 percent, growth will be limited. The dollars and high hopes invested in a hydroponic system can easily be 'dashed' in a cloud of hot, humid air.

Air 20%
- Temperature
- Humidity
- CO2 and O2 content

Light 20%
- Spectrum
- Intensity
- Photoperiod

Water 20%
- Temperature
- pH
- EC
- Oxygen content

Nutrients 20%
- Composition
- Purity

Growing Medium 20%
- Air content
- Moisture content

So according to the major's post, higher temperatures brings your growth potential down between 75-80% yield. And this of course may not apply to all strains because of origin and also takes under consideration very high and very low temps, so I'd assume the actual number is more like 85% when applying to your individual case. Plus from what I can tell the usage of Co2 also "calms the storm" on high temperatures... so to speak. So in my opinion the bottom line is temperatures probably do effect yield. We compare plants to humans a lot, and if we did it here; humans do struggle in higher temperatures while being physically active and eventually get stressed and slow down, so why shouldn't plants? Of course those who live in the desert and have their whole lives may be able to run a marathon, so whether or not the climate plays a large factor is up to those who know. -d.oz

Any thoughts major?

 

[nongreenthumb]

I'm only a newb ngt, and I've always wondered the same thing as my grow room often runs higher than needed. Based on the information I've read so far it seems that your speculation on climate is true. The other thing is that marijuana may grow in high temperatures but it may not flourish. You get what I mean? It's just another factor that effects yield, so I'd suspect that if you had high heat but optimal growth factors in other areas your yield would be pretty nice, just not as nice as it would have been since it seems heat slows down growth to some degree (to what degree I have no idea).

P.S. I found the post I was looking for. Here it is - -




So according to the major's post, higher temperatures brings your growth potential down between 75-80% yield. And this of course may not apply to all strains because of origin and also takes under consideration very high and very low temps, so I'd assume the actual number is more like 85% when applying to your individual case. Plus from what I can tell the usage of Co2 also "calms the storm" on high temperatures... so to speak. So in my opinion the bottom line is temperatures probably do effect yield. We compare plants to humans a lot, and if we did it here; humans do struggle in higher temperatures while being physically active and eventually get stressed and slow down, so why shouldn't plants? Of course those who live in the desert and have their whole lives may be able to run a marathon, so whether or not the climate plays a large factor is up to those who know. -d.oz

Any thoughts major?

We all know though that with higher temperatures and increased co2 levels the plant will produce more/

 

[frog3850]

the grow room temps are only a guideline with heat comes humidity and with humidity comes fungus and mold and pests. keeping your grow room below 85 degrees and a at 50 % humidity will help the plant to transpire (breathe) easier and help to ward off the pests and diease. savtias can handle more heat due to where they come from warmer climates (note the smaller leaves). indicas cant handle as much heat because they come from colder temps with less light (hence the bigger leaves) so temp is a fact.

 

[mogie]

Your standard mercury/alcohol-bulb or digital thermometer is designed to measure the temperature of the air (But not radiant heat).

Radiant temperature is the result of heat transfer bewteen objects at different temperatures without whats inbetween i.e. the air, being effected. In our case the plants are naturally at a lower temperature that the light and reflector so heat is transferred to the plants foliage from the light/refecltor through radiation. This causes the leaves to heat up. The plants can withstand much higher radiant temperatures (around 40-50degC) than they can air temperatures but if this is too high the plants can 'burn'.

The plants can withstand much higher radiant temperatures than they can air temperatures, but if this is too high the plants can “burn”.

 

[nongreenthumb]

the grow room temps are only a guideline with heat comes humidity .

Thats 100% false right there. In my grow room last night temperatures reached 104 f and yet still humidity was only at 19%. Where I am I get low humidity which is why I have to mist my clones so much.

Humidity comes from water temperature being higher than air temperature.

 

[SnowWhite]

Interesting discussion here. I'm growing Mandala genetics partly becuase they are supposed to cope with high temps.....but like you suggest NGT, marijuana must have a high heat tolerance by default becuase of where it grows around the globe.

When I was growing my snow whites earlier this year, before I had my intake fan, I just had passive vents. When we had our early summer here in the UK (before all the rain) temps would reach 38C in my green house during the day. My plants did not suffer with any heat problems/stress and this is not a strain known for it's heat tolerance......so go figure! Maybe if I'd been able to maintain temps around 25C I would of yielded more, but who knows!?

In winter I should be able to maintain my green house at 24-26C with lights on, so it will be interesting to compare my winter and summer yields.

 

[TheConstantGardner]

Thats 100% false right there. In my grow room last night temperatures reached 104 f and yet still humidity was only at 19%. Where I am I get low humidity which is why I have to mist my clones so much.

Humidity comes from water temperature being higher than air temperature.

Excellent point, great thread

 

[McGruppsMonsters]

I think hot air technically CAN hold more water, but GreenThumb is right on this one... high temps don't always equal high humidity otherwise people would keep their rooms cold during flowering in order to keep their humidity down.

 

[natmoon]

I think the truth is that weed can grow in just about any situation,its really all about striving to find perfect conditions to create perfect plants.

My real attitude to weed is that if you stuck a seed in your asshole and pointed it at the sun for long enough it would grow out of your dying ass and be a half decent smoke,but i do enjoy all the technicalities and ways that more and better buds may be achieved.

So my answer is that i think controlling the temperature to some degree will create a better atmosphere for the plants to grow in,what that perfect temp is i dont know and whether or not any one given temp is suitable for every strain is for scientists to work out

 

[nongreenthumb]

Last night by growroom kept a steady 95, relative humidity was just 15%

 

[FilthyFletch]

The high temps tell the plant to slow down and stop to conserve energy and moisture. At those temps your plant attempts to survive and goes into a slow motion grow. You add time and loose yield and potency as the plant uses its resources ina conserved mode. In nature the plant has the ability to allow its roots to search out and replenish itself which stops the alert mode the plant has for survival. I have grown at optimol 78 degrees F and had grows that hit high 90's during the day. Same clones from same mome and you will see a huge difference in the cooler grown plants. Temps of 90 with optimol 1500 ppm can be used as the co2 allows the leaves pores to open wider and cool faster which inturn allows better in take of misture to the leaves feeding and nurturing the plant.If the temps are high and co2 is low your plant will stunt and slow down and eventually can die.

 

[nongreenthumb]

The high temps tell the plant to slow down and stop to conserve energy and moisture. At those temps your plant attempts to survive and goes into a slow motion grow. You add time and loose yield and potency as the plant uses its resources ina conserved mode. In nature the plant has the ability to allow its roots to search out and replenish itself which stops the alert mode the plant has for survival. I have grown at optimol 78 degrees F and had grows that hit high 90's during the day. Same clones from same mome and you will see a huge difference in the cooler grown plants. Temps of 90 with optimol 1500 ppm can be used as the co2 allows the leaves pores to open wider and cool faster which inturn allows better in take of misture to the leaves feeding and nurturing the plant.If the temps are high and co2 is low your plant will stunt and slow down and eventually can die.

Sounds good but i'm not sure how true this is.

 

[FilthyFletch]

Try it out if you have the room grow some at 78 F and some at 98 and it will show a great difference in yeild and quality as the resins get used by the hotter plants to stay cool and they slow growth.The cooler will be nice and happy and sticky

 

[FilthyFletch]

and side note what the hell is that chart thing you got there lol I see it and cant figure it out

 

[SnowWhite]

The high temps tell the plant to slow down and stop to conserve energy and moisture. At those temps your plant attempts to survive and goes into a slow motion grow. You add time and loose yield and potency as the plant uses its resources ina conserved mode. In nature the plant has the ability to allow its roots to search out and replenish itself which stops the alert mode the plant has for survival. I have grown at optimol 78 degrees F and had grows that hit high 90's during the day. Same clones from same mome and you will see a huge difference in the cooler grown plants. Temps of 90 with optimol 1500 ppm can be used as the co2 allows the leaves pores to open wider and cool faster which inturn allows better in take of misture to the leaves feeding and nurturing the plant.If the temps are high and co2 is low your plant will stunt and slow down and eventually can die.

Interesting, thanks for this info. I'm looking forward to winter when I will be able to keep my grow room at optimal temps no problemo, so I'm very interested to see what my winter 'indoor' harvests yeild, compared to summer when my grow room temps are on the high side!

 

[FilthyFletch]

I almost guarantee you will see a difference right away if you had those high 90s summer temps.Good luck and post back to this thread with your findings

 

[McGruppsMonsters]

Anything over 85 degrees without question not only decreases yield but also potency of the herb. You can push a bit higher if you are burning c02 as someone already said, but I try to keep things in the canopy under 85. I read 76-79 degrees is the temp in which photosynthesis is conducted the easiest and most effeciently. good luck