Humidity

[TedeBoy]

I'm running autoflower White Widows on a 20/4 light cycle.
I keep my circulation fans on 24/0.
The exhaust fan is on a thermostat.
I'm running temp/rh about 76F/60rh.

My humidity spikes up during the 4 hours of lights off to 80-85 rh.

Is this a problem?
What can be done?
Maybe just run a 24/0 light cycle since they are autoflowers?

Thanks for your thoughts on this.

They are 9 days old.

 

[DesertGrow89]

Yep I had the same problem. I bought a 50 pint dehumidifier to keep it down, it's more of a problem in flower than it is in veg. Interested in hearing if anyone else has cheaper solutions.

 

[GreenSanta]

I would do 24-7, cheaper than running a dehumidifier. Dont water all your plants at once, simply water 2 pots a day at most. Ideally, you want to keep it below 50 late in flower if the buds are big. The main issue with high RH will be mold in your closet or basement, not good...

 

[a senile fungus]

If the exhaust fan is on a thermostat, does it shut off for 4hrs during your lights out?

That might be your issue. Try exhausting all the time to remove the water vapor that the plants transpire during their night.

 

[TedeBoy]

If the exhaust fan is on a thermostat, does it shut off for 4hrs during your lights out?

That might be your issue. Try exhausting all the time to remove the water vapor that the plants transpire during their night.

Yes. When the light goes out, temps drop, and the exhaust fan stays off.
It's easy for me to control tent temp on a thermostat. Not sure how to if the fan is on constantly. It does have a variable speed control so I could try but the ambient outside temp is so variable I'd be adjusting constantly.
I'm gonna try adjusting the water schedule so they aren't watered before lights out. Or water only two at a time as suggested.

 

[DesertGrow89]

Yes. When the light goes out, temps drop, and the exhaust fan stays off.
It's easy for me to control tent temp on a thermostat. Not sure how to if the fan is on constantly. It does have a variable speed control so I could try but the ambient outside temp is so variable I'd be adjusting constantly.
I'm gonna try adjusting the water schedule so they aren't watered before lights out. Or water only two at a time as suggested.

You should water shortly after lights on, no more than an hour after IMO.

 

[Humanrob]

I was going to start a thread about this, but since this one is already in play...

Besides mold/mildew, are there any other issues with having too much humidity?

Does it impact plant growth or bud size or potency...?