Humidity levels in flower?

westpoint

Well-Known Member
I have watched and read 100 pieces on humidity and temp. I am in a 3x3 tent with temps sitting at 78, humidity would get up to 63% 4 weeks in flower. I purchased a cheap dehumidifier and have humidity sitting around 55%. My canopy is thick, I want to know if this is a safe level to finish my ladies out in. Thanks.
 

ZuuTeD614

Well-Known Member
60 percent humidity is fine with that temp or if you can get it around 82 just have plenty of air circulation so you don't get mold issues. You also don't need the fan smashing your plant a nice draft past the canopy is fine. I run 79-84 with 60-70 RH veg-harvest. Never had PM or Bud Rot, nothing! Goodluck! :blsmoke:
 

westpoint

Well-Known Member
60 percent humidity is fine with that temp or if you can get it around 82 just have plenty of air circulation so you don't get mold issues. You also don't need the fan smashing your plant a nice draft past the canopy is fine. I run 79-84 with 60-70 RH veg-harvest. Never had PM or Bud Rot, nothing! Goodluck! :blsmoke:
saweeet. ty.
 

westpoint

Well-Known Member
60 percent humidity is fine with that temp or if you can get it around 82 just have plenty of air circulation so you don't get mold issues. You also don't need the fan smashing your plant a nice draft past the canopy is fine. I run 79-84 with 60-70 RH veg-harvest. Never had PM or Bud Rot, nothing! Goodluck! :blsmoke:
is 82 better than 77, 78, if so I can turn my fc 4800 to max. :)
 

Rurumo

Well-Known Member
82 is perfect with LEDs. You'll find that the RH% in the canopy is much higher than the RH in your lung room, but like westpoint said, humidity doesn't usually cause problems in healthy plants as long as you have ample air circulation. It's a good idea to remove some foliage under the canopy until you can look in there and see every leaf at least moving slightly in the breeze. Having a fan underneath the canopy is a good idea.
 

Alfadog#1

Well-Known Member
Canopy temp if you have a IR gun should be around 86.5 I aim for ambient room temp 83-84 as others said the lack of infrared led emits the higher temps help the metabolic rate and stomata functioning properly so you will experience much higher quality and yeilds if you respect these parameters and I'd drop the humidity as best as possible to atleast 50-55 if you increase those temps be prepared the stomata will function better and plant will sweat more in a lack of words and humidity will be added to your initial so try getting that fixed and learning to control all your parameters rather than conforming because one day you might have a strain very dense and wtv the issues and don't have control over your room isent a wise idea
 

Billy the Mountain

Well-Known Member
Canopy temp if you have a IR gun should be around 86.5 I aim for ambient room temp 83-84 as others said the lack of infrared led emits the higher temps help the metabolic rate and stomata functioning properly so you will experience much higher quality and yeilds if you respect these parameters and I'd drop the humidity as best as possible to atleast 50-55 if you increase those temps be prepared the stomata will function better and plant will sweat more in a lack of words and humidity will be added to your initial so try getting that fixed and learning to control all your parameters rather than conforming because one day you might have a strain very dense and wtv the issues and don't have control over your room isent a wise idea
No, LST shouldn't be that high

LST will be ~3-5°F below ambient with a healthy, transpiring leaf under LED lighting
 

Mont@n@

Well-Known Member
I have watched and read 100 pieces on humidity and temp. I am in a 3x3 tent with temps sitting at 78, humidity would get up to 63% 4 weeks in flower. I purchased a cheap dehumidifier and have humidity sitting around 55%. My canopy is thick, I want to know if this is a safe level to finish my ladies out in. Thanks.
Grow based of your Vapor Pressure Deficit (VPD)

VPD Chart
https://cerescann.com/an-introduction-to-vapor-pressure-deficit/

34288B71-C7BB-4F45-A888-1A1EEF06D40B.jpeg
25 cxb3590 at 1250 watts 5x5
My flower room temperature
80.6f - 82.4f (mini split a/c, CO2 700ppm)

My safe zone RH% with air circulation based on that chart is:

RH% VPD (kPa)
85% - 0.54 Fungal Pathogens
80% - 0.71 MAX (big chance of fungal)
75% - 0.89 x Safe Zone Max
70% - 1.07
65% - 1.25
60% - 1.43
55% - 1.61 x Safe Zone Min
50% - 1.78 Min
45% - 1.96 High Stress Zone

I hope it helps and by the way this chart hasn’t failed me good luck
Happy growing
 
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ComfortCreator

Well-Known Member
Lighting levels also need to be managed, increasing the intensity is good up to a point after which it can stress the tops. So even though you could increase to max you should measure it and know what you are doing.
 

Alfadog#1

Well-Known Member
That makes no sense what does "low stress training" have anything to do with temps one is talking about temp and you come in talking about technique do what you want iv done 1 run temps at canopy at 86.5 and results where amazing went down to 82.5-83.5 and got slightly smaller and fluffier harvest and now I'm back to my old parameters and recreated more to the previous crop if you haven't tested dont post it anywhere and everywhere will explain this when it comes to leds
 

Alfadog#1

Well-Known Member
As long as the canopy reads 85.5-86.5 normally your ambient temp in 3-5 degrees lower so the stomata functions at its best and you will get a better exchange of co2 and oxygen and the plants will have a better perspiration and photosynthesis its not bro science
 

FirstCavApache64

Well-Known Member
As long as the canopy reads 85.5-86.5 normally your ambient temp in 3-5 degrees lower so the stomata functions at its best and you will get a better exchange of co2 and oxygen and the plants will have a better perspiration and photosynthesis its not bro science
Leaf surface temperature is almost always lower than ambient air temperature unless there's a problem. That's not bro science, that's a fact. If your leaf surface temps are higher it means your lights are too close or something else is going on. Healthy plants transpiring correctly will usually be about 2-2.5 degrees Celsius cooler than ambient air. I've been reading leaf surface temps for several years with quite a few grows and that's a constant.
 

FirstCavApache64

Well-Known Member
That makes no sense what does "low stress training" have anything to do with temps one is talking about temp and you come in talking about technique do what you want iv done 1 run temps at canopy at 86.5 and results where amazing went down to 82.5-83.5 and got slightly smaller and fluffier harvest and now I'm back to my old parameters and recreated more to the previous crop if you haven't tested dont post it anywhere and everywhere will explain this when it comes to leds
LST is leaf surface temperature not low stress training. So.....
 

LeastExpectedGrower

Well-Known Member
The only place I've heard of people with LST that's higher than tent/room temps is people who are not using LED lighting. Generally speaking with LEDs the LST is lower but a few degrees.

In my case, it's about 2.5f degrees lower than ambient room temperatures. So my setup is dialed to pull more air once the tent hits 85f degrees (making LST 82 to 83f). I do my best not to fall too far below 78f in the tent so the LST isn't falling below 75f.

Checking LST is pretty cheap and easy with plenty of decent IR thermometers out there for under 30 bucks.
 

Alfadog#1

Well-Known Member
The only place I've heard of people with LST that's higher than tent/room temps is people who are not using LED lighting. Generally speaking with LEDs the LST is lower but a few degrees.

In my case, it's about 2.5f degrees lower than ambient room temperatures. So my setup is dialed to pull more air once the tent hits 85f degrees (making LST 82 to 83f). I do my best not to fall too far below 78f in the tent so the LST isn't falling below 75f.

Checking LST is pretty cheap and easy with plenty of decent IR thermometers out there for under 30 bucks.
"There is a prevailing consensus that 75 °F is the ideal ambient temperature to grow Cannabis under HPS lighting without CO2 supplementation. This experimental result indicates that an 84 °F ambient air temperature is required to achieve the same optimal leaf surface temperatures when using plant-optimized LED lighting-- and that a 75 °F ambient air temperature with LED lighting would not achieve optimal leaf surface temperatures, slowing metabolic rates and leaf and flower production."

If you want more articles you could find them yourself hps and leds are a whole different style of growing every factor humidity or temps air flow and the ways even wind hits the plants might affect (leaf surface temps) that's why I say using your IR gun measuring at the canopy is more true than ambient temps.... many people run into issues they never would think of as not over watering but plants exhibit sign of over watering like wilting could be lack of oxygen to the roots because not enough perlite and takes too long between watering which could also deplete nutrients in soil or not enough Transpire through stomata due to low surface temps and poor exchange of c02& oxygen
 
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