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.
Humidity levels in flower?
- Thread starter westpoint
- Start date
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! 
saweeet. ty.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!
is 82 better than 77, 78, if so I can turn my fc 4800 to max.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!
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
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
Grow based of your Vapor Pressure Deficit (VPD)
VPD Chart
https://cerescann.com/an-introduction-to-vapor-pressure-deficit/
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.
ZuuTeD614
Well-Known Member
Yup 100 percent my Temps stay 80-84 and kesf tenps are about 77-80
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
FirstCavApache64
Well-Known Member
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
LST is leaf surface temperature not low stress training. So.....
Southernontariogrower
Well-Known Member
I let it jump, 90+ degrees 80 to 85 rh supplimented co2 in 4x4 with 9 8g Lit Farms georgia runtz, 70 day veg, filled tent full. No pm, no budrot. Damn good run for me. Crispy leaves but bud was sweet and skunkier then l suspected. Pots then stalks followed by a few feet of canopy then colas to the light. No room for me to raise light 
Alfadog#1
Well-Known Member
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.
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.
need par meter?
Alfadog#1
Well-Known Member
"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