What Humidity % for during flower???

[Doc50holliday]

Humidity is relative to the temperature in the room. Everyone says to bring the humidity down to 30-40% at the end of flower but at what temperature?

Bringing RH down to 30-40% at 85 degrees gives you a dew point of 50-58 degrees

If you drop temps at the end of flower (like many do) it would be insanely hard to bring your humidity down to 30-40%

Let's say you drop to 68 degrees at the end of flower, to achieve the same dew point of 50-58 degrees you would only need an RH of 53-70% to achieve the same dew point.

I really think we should be more specific when talking about dropping humidity at the end of flower...

If someone were to drop to 30-40% humidity at 68 degrees, their dew point would be between 35-43... That's a very different environment than the person who's at 85 degrees 35% humidity who has a dew point of 50-58

 

[Humboldtcalikidd]

I know this a old thread but the term is a vpd chart! Look it up hope this helps

 

[Doc50holliday]

I know this a old thread but the term is a vpd chart! Look it up hope this helps

Thanks for the contribution! Yeah, I’m well aware of the VPD levels and what not. I was more specifically aiming my response at the concept of

“dropping humidity levels to 30-40% at the end of flower for trichome production”

At this point we are straying from VPD because we’re no longer trying to achieve bud growth but are trying to make the plant thing that winter and fall is coming for additional trichomes.

I was saying that 30-40% at 80 degrees is different than 65.. simply giving the RH isn’t enough info to try and implement this approach. I almost think the dew point would be a better measure, but not positive.

 

[Star Dog]

Thanks for the contribution! Yeah, I’m well aware of the VPD levels and what not. I was more specifically aiming my response at the concept of

“dropping humidity levels to 30-40% at the end of flower for trichome production”

At this point we are straying from VPD because we’re no longer trying to achieve bud growth but are trying to make the plant thing that winter and fall is coming for additional trichomes.

I was saying that 30-40% at 80 degrees is different than 65.. simply giving the RH isn’t enough info to try and implement this approach. I almost think the dew point would be a better measure, but not positive.

I've commented a couple of times about taking/accepting the rh% that comes with the temperature that day, idk how others manage to control rh and temp separately without a shed load of hardware.

A environment controller switches on with temperature and humidity, htf does one not affect the other without a shed load of hardware, it's a joke?

 

[Doc50holliday]

I've commented a couple of times about taking/accepting the rh% that comes with the temperature that day, idk how others manage to control rh and temp separately without a shed load of hardware.

A environment controller switches on with temperature and humidity, htf does one not affect the other without a shed load of hardware, it's a joke?

Well of course.. Obviously if people are talking about dropping temps / dropping humidity within a certain time frame then they're going to have to manipulate the environment some how.. You're going to need AC units and dehumidifiers.

 

[Puff_Dragon]

FYI -
my tent is 1m2 and two meters high.
I need to run a 6" intake fan (pulling air from outside the house into the tent) 24/7 during flower. To keep humidity at 50 or below.

 

[Humboldtcalikidd]

I live In Southern California and very little humidity down here. I really can’t afford big humidifiers for growing and dehumidifies for drying during my grows. So whatever it may be that day I just roll with it. In reality I need more rh in veg and early flower but I think I grow great weed without rh being perfect. But if you want to hit your plants with a lot of light then your environment needs to be more in check. We will see how things change for me as I just got a new led light 660w moved from a cmh.

 

[ilovetoskiatalta]

Keep in mind that there is no set rule for every grow, these values are merely guidelines for the grower to work with.
Your environment, how it behaves, what is interacting with, will have a lot to do with how things are set.
Also, your equipment is important as well. All that hardware adds to heat...
Different strains will also behave differently under set rules, you have to be flexible or "dynamic" as needed...
I'm working a 1200 plant GG with 10 rooms. Some of our biggest challenges are with equipment. As we add dehu's, heat is an issue and the a/c's can't keep up, things like that. Also, PM. Keeping things cool and dry enough at night to limit outbreaks...

But on topic, we run veg @65-75 rh
week 1 flowr @ 60ish
Week 2/3 is where we begin to work this down, 55ish
You can run this through week 5/6 around 45-55. your plants(strain) will show you what they prefer...Watch Them Closely.
With our feed program, we are getting massive bud swell late in week 6 into week 7. Dropping RH at this time and adjusting temps down in the last week is huge. The problem here is the DP(Dew Point). We do not have heaters in our rooms and temps are still dropping (outside) to -8C.
As the temps drop, so does the DP and the Dehu's are icing up trying to keep up. We are forced to increase day temps and RH just so we can get through the night before lights on. For instance, I have to keep my night temps above 70 and rh above 40, just to stay a step above DP so the equipment keeps running and reduce mold risk.
Sometimes, it's not so much what you want to do, but what can you do...

@KidKnicky So that is what happens late May early June with the a/c...the DP makes them ice up before sunrise

 

[Adi1989]

For veg and up to the end of intial stretch in flowering...50% to 65% (read up on vapor pressure deficit).

For the rest of flowering,no more than 50%.

The last 2 weeks you can try dropping it to about 30% to see if it makes your buds pack on a few more trichomes.

So typically would you say go down to 40/50% humidity 3 weeks or 4 weeks after flipping to 12/12?