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How important is ventilation?

F. Dupp

F. Dupp

Active member
Veteran
I have recently started up in a new place. Its a pole barn with spray foam insulation that is pretty airtight. My plants have adequate light, water, nutes, and the indoor temps range from 50f to 86f. The humdity ranges from 35% to 80% depending on day/night. My plants are 4 days into flower and are starting to look like shit. Leaves are curling downward with little to zero new growth. While I have always vented my rooms to avoid heat issues, I am facing problems with the cold now. Im afraid to bring outside air in, as it has been around -2f here all week. Are my plants struggling from lack of fresh air, or is it something else? I have also been running a vent free propane heater on occasion to keep up nighttime temps.

Thanks for any advice
 
FletchF.Fletch

FletchF.Fletch

Well-known member
420giveaway
Ventilation is an important component. Air exchange makes for healthier plants, air movement fights fungal growth.

Sounds like they might be responding negatively to cold night temperatures. If possible elevate plants above the floor if the ground area is cold, keep air moving even around the containers the plants are in, and monitor your temperatures closely.

Hope this helps. Good Luck!!
 
Last edited:
R

Roadblock

Active member
F. Dupp said:
I have recently started up in a new place. Its a pole barn with spray foam insulation that is pretty airtight. My plants have adequate light, water, nutes, and the indoor temps range from 50f to 86f. The humdity ranges from 35% to 80% depending on day/night. My plants are 4 days into flower and are starting to look like shit. Leaves are curling downward with little to zero new growth. While I have always vented my rooms to avoid heat issues, I am facing problems with the cold now. Im afraid to bring outside air in, as it has been around -2f here all week. Are my plants struggling from lack of fresh air, or is it something else? I have also been running a vent free propane heater on occasion to keep up nighttime temps.

Thanks for any advice
Click to expand...

Fresh air flow is super important without it you are asking for root problems unless you run a totally controlled closed system and gassing them.

If you are battling cold run your intake air through cool tubes so the air gets heated by the lights without restricting the flow, its much more efficient to heat the intake air than it is to try to warm the room space when bringing in really cool air.
 
F. Dupp

F. Dupp

Active member
Veteran
I opened an outside door a crack and allowed fresh air in for about 2 hours. With the lights running it only dropped the temps at the canopy down to 76f. I run a low pressure aero system, and the plants seem to be drinking and eating fairly well, they just look like shit. Kinda soggy like.
 
F. Dupp

F. Dupp

Active member
Veteran
dramamine said:
I had those symptoms from running a propane burner in a sealed room.
Click to expand...


I have removed the propane heater and added an electric space heater with thermostat control so that temps cant dip below 63f. The room itself is very well insulated with both spray foam and fiberglass insulation.
 
F. Dupp

F. Dupp

Active member
Veteran
Ok. It was definitely the propane heater causing all of my problems. Once I removed it, all of the symptoms disappeared. DO NOT use propane heaters in poorly ventilated rooms.

Thanks, Dramamine
 
f-e

f-e

Well-known member
Mentor
Veteran
A co2 monitor might of been illuminating. Just a candle is a lot of co2 in a sealed space. A full on heater sounds like a co2 boost of some proportion, even in a big barn. That extra co2 will place a demand on feed. I would want to look it up, but it sounds like P def at a time when P is in great demand. Jacks new canna food is 10-30-20 at this time. So perhaps you had a huge P demand.

I guess the heater was on mostly lights off. So both heater and plants were using oxygen and giving off co2. A conflict of interest. I have no idea what a lack of night-time oxygen looks like.. It's rare we even talk of it.
 
troutman

troutman

Seed Whore
Humidity swings that large will cause plant stress. I got a dehumidifier for this grow to stop
the rise after the lights go out. I turn it on minutes before the lights go out and leave it on
until the lights come back on. You don't want more than 60% humidity when plants flower
and preferably around 50% at the end to avoid moldy buds. If you don't deal with the
humidity it will eventually cause mold and other problems in the house itself as well.
 
f-e

f-e

Well-known member
Mentor
Veteran
troutman said:
Humidity swings that large will cause plant stress. I got a dehumidifier for this grow to stop
the rise after the lights go out. I turn it on minutes before the lights go out and leave it on
until the lights come back on. You don't want more than 60% humidity when plants flower
and preferably around 50% at the end to avoid moldy buds. If you don't deal with the
humidity it will eventually cause mold and other problems in the house itself as well.
Click to expand...

I forgot to address this. 80% is just not going to work. I have outdoor strains that won't hack that. Thankfully is very cold outside though so perhaps a makeshift dehumidifier will work. Just bringing cold air in, through a really long duct, will cause condensation upon it as it warms the inlet air also. Though it need not be inlet air, it could go straight back out. Just having such a cold surface will get the moisture condensing upon it. 2F? that's like minus something right? my dehu~ isn't that cold
 
troutman

troutman

Seed Whore
I sometimes open my window just enough to allow a sheet of paper to pass thru
for extra ventilation during the day when the lights are on to vent off extra heat.
As long as your there to monitor the temps you won't chill anything.
 
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