Ideal humidity for flowering?

The Hippy

Well-Known Member
Was talking with a pro the other day. He felt under 50% was a tad low for flowering. I hate mold.
What's everyones thoughts on the perfect % for humidity in flowering.
I'm at 40-45%...maybe too low.
 

zoic

Well-Known Member
Was talking with a pro the other day. He felt under 50% was a tad low for flowering. I hate mold.
What's everyones thoughts on the perfect % for humidity in flowering.
I'm at 40-45%...maybe too low.
From my observations the humidity tends to level off at 40-50 when I switch to 12/12. I expect it would depend on many things like hot much heat your lights chuck, how big your space, how much air flow etc.. I have had a few occasions when the humidity was 70%, so I just open the tent for awhile to let some air our, LOL
 

NGA

Well-Known Member
I've been growing for ever it seems never have any idea how humidity is my exhaust fan is on 24-7 ,all I know is to much is to much if your leaves are wet they will end up burning when lights come on
 

GreenHighlander

Well-Known Member
I run 40-50% in flowering depending on time of year. Sometimes in winter it will even be closer to 30% with lights on. Lights off it stays around 60-70% at most.
I will say they prefer higher humidity in veg, but I am ok with running lower humidity in flowering.
Cheers :)
 

HotKarl2

Well-Known Member
Humidity levels depend on temps..dial in your VPD (Vapor Pressure Deficit). Typically, the higher your temps, the higher your humidity should be. The gold fields on the chart are optimal ranges for Cannabis.

View attachment 4117924
Took a look at that chart. At 29c my humidity should be 75-80%? Can you say bud rot and mildew? I've gotten bud rot indoors at 60% humidity and 80-90F (27-32C). I'd say that chart is a bit off.

My duhumidifier keeps my room at 50% during flower to avoid bud rot especially on large dense colas.
 

The Hippy

Well-Known Member
Took a look at that chart. At 29c my humidity should be 75-80%? Can you say bud rot and mildew? I've gotten bud rot indoors at 60% humidity and 80-90F (27-32C). I'd say that chart is a bit off.

My duhumidifier keeps my room at 50% during flower to avoid bud rot especially on large dense colas.
I felt it seemed like too much humidity as well. The chart seems to favor TOO humid imo. But I never claim to be an expert....unless it's hating on the LP's...then I'm a pro.
I agree Karl....70% seems to high to me????
 

HotKarl2

Well-Known Member
I still don't understand the numbers in the middle of the chart. I must be blasted or stupid or both.
:shock:
I think that must be the humidity at/in the canopy and not in the room. Keep your ROOM at 50% and your canopy will be higher.
 

natureboygrower

Well-Known Member
I still don't understand the numbers in the middle of the chart. I must be blasted or stupid or both.
:shock:
from what i understand,and a different chart ive read somewhere,you drop humidity the further into your flowering weeks.weeks 1-2 humidity is stupid high(not any buds formed),3-4 its a little lower,and so on.i had a humidifier in my cab at one point to try and match that chart but stopped.i moved indoors to avoid rot.
 

HotKarl2

Well-Known Member
from what i understand,and a different chart ive read somewhere,you drop humidity the further into your flowering weeks.weeks 1-2 humidity is stupid high(not any buds formed),3-4 its a little lower,and so on.i had a humidifier in my cab at one pount to try and match that chart but stopped.i moved indoors to avoid rot.
Yep that is totally true. Reduce humidity especially towards the end of the cycle or you will get rot. Rot sucks. And watch your canopy humidity. Packed colas have much higher chance of rot.
 

TheRealDman

Well-Known Member
I still don't understand the numbers in the middle of the chart. I must be blasted or stupid or both.
:shock:
The gold fields are ranges of ok (7.5), to optimal (10.5).

Do your plants pray towards the light? If so, chances are your VPD is on point.

Budrot indoors is a result of high humidity, with a lack of adequate air movement...IMO.
 

The Hippy

Well-Known Member
The gold fields are ranges of ok (7.5), to optimal (10.5).

Do your plants pray towards the light? If so, chances are your VPD is on point.

Budrot indoors is a result of high humidity, with a lack of adequate air movement...IMO.
Range of what? 7.5 what?
 

MichiganMedGrower

Well-Known Member
Humidity levels depend on temps..dial in your VPD (Vapor Pressure Deficit). Typically, the higher your temps, the higher your humidity should be. The gold fields on the chart are optimal ranges for Cannabis.

View attachment 4117924

This chart is actually for Greenhouse agricultural crops. People started posting it a while back on weed sites and now it’s ideal for cannabis?

I keep my room at 50-60% rh max to avoid mold. And 75-77 degrees Fahrenheit for best potency and terpenes.

Too dry causes excessive transpiration.
 
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