How important is air flow?

Hi i was just wondering how important it is to have a fan set up in a grow room.
Does it increase yield atall.?
cheers guys +rep for help

There is a scientific answer, but basically the plant uses the air around it quickly, the quicker you can replace it, the more energy the plant accumulates. Also research CO2...

extremely, a fan is a must along with venting and good air circulation.

Now you cant just have a sealed room with a fan blowing the same air on the plants, you need a fresh air source. I gots one of them dang ol' inline fans brother, works wonders if you need air flow as well as lowering temp...

I always say mimic nature as best as you can.

A fan in the grow room mimics winds in nature. With that in mind, a fan does two important things. First is air circulation. Like FLABOY1 said, the leaves will use up the carbon dioxide that's nearby the leaf within a few minutes. So, you've got to circulate the air because the plant can't exactly run around breathing. Like darkdestruction420 mentioned, venting, or getting rid of old air, is important as well. There must be an exchange in air so that carbon dioxide is always available. The second is that plants react to stimulus. They react to wind by stiffening their stems. So, a fan will signal that the plant should use some energy to strengthen its stem. Of course this is important because as marijuana begins to flower, those buds get real fat and heavy. You don't want a plant with a weak stem that may simply topple over from the weight of its buds.

is CO2 good for veg too?

plants produce (O2) by taking in (Co2)+(H2O), eating CH2O and releasing O2 back into the atmosphere.

plants use the Co2 around the leaves around once/min (that means it NEEDS to be replaced once/min. not hard in small rooms, good ventalation will do this)

your plants need 3 main things. Carbon dioxide, water, and light. they produce oxygen, like we produce carbon dioxide.

plugsmustard said:

is CO2 good for veg too?

Click to expand...

Co2 is needed in all stages of growth. its the plants MAIN food source, without the chlorophyll (CH2O) the plant cant move the nutrients and oxygen it absorbs through its root system.

Co2 tanks aren't always a necessary expense, with decent ventilation enough Co2 is supplied to the room that the tank would be a waste (being vented out of the room anyways.....)

NO co2 is bad for veg, never do it unless u want to fuck ur plants......

I agree that aircirculation is key but how do u explain sealed rooms that have co2 and only have fans blowing the existing air around, set ups like those still pull great numbers.....

lifesgood said:

NO co2 is bad for veg, never do it unless u want to fuck ur plants......

I agree that aircirculation is key but how do u explain sealed rooms that have co2 and only have fans blowing the existing air around, set ups like those still pull great numbers.....

Click to expand...

NO o2 is bad for babies!!!

now doesn't that sound stupid? maybe someone cut your air off when you were a kid.

see my previous post that shows how Co2 is like oxygen to humans.


the leaves of all plants work like this.

Don't give too much co2. As long as you don't supplement you won't have to worry about that. Air circulation is definitely helpful... I've never grown as well as when i visited my plants multiple times a day and spent minutes breathing on them as i inspected them. Perhaps it was the co2... and perhaps it was the love. Regardless, nurture them and they'll treat you well. (I speak as someone that's gotten 3x as much from the grows i've watched over every few hours as opposed to the ones i would only check 1-2 times a day)

Redeflect said:

Don't give too much co2. As long as you don't supplement you won't have to worry about that. Air circulation is definitely helpful... I've never grown as well as when i visited my plants multiple times a day and spent minutes breathing on them as i inspected them. Perhaps it was the co2... and perhaps it was the love. Regardless, nurture them and they'll treat you well. (I speak as someone that's gotten 3x as much from the grows i've watched over every few hours as opposed to the ones i would only check 1-2 times a day)

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yea this is true, the last auto watering grow i had i was checking it once a week or so, this current one with soil is being checked every few hours and the growth is much more vibrant and rich.

Corbat420 said:

NO o2 is bad for babies!!!

now doesn't that sound stupid? maybe someone cut your air off when you were a kid.

see my previous post that shows how Co2 is like oxygen to humans.


the leaves of all plants work like this.

Click to expand...

LOL ok go nuts, pump ur lil babies in veg full of co2 then tell me what happens.... get some hands on expeiarence before u open ur mouth.. in theory yes co2 should be good at all times of plant growth ( veg & bloom) however in practice this is not the case.......

NEVER USE CO2 IN VEG . TRUST ME

so too much c02 is bad

as far as fans go, they are a must to keep air circulating.

i was so worried about getting air flowing
in my grow box that i used one of those
big fans from inside a ps3 and mounted
it inside my grow box.

NOTE FOR MICRO GROWERS: ps3 fan works much better then a pc fan in a grow box

gotta have fans....i use three for about 20 plants....one fan hangs blowing the heat that is coming from the light to the plant...the second and third fans ocilate the room and are on opposite ends of the grow table

1. How long should air flow circulate in Vegetation 24 hours or 18/6 ?
2. How long should air flow circulate in Flowering 24 hours or 12/12 ?

Asking in terms of saving energy,

lifesgood said:

NO co2 is bad for veg, never do it unless u want to fuck ur plants......

I agree that aircirculation is key but how do u explain sealed rooms that have co2 and only have fans blowing the existing air around, set ups like those still pull great numbers.....

Click to expand...

please explain how it fucks up plants.


sealed rooms work b/c the air quality is dialed in

Please explain how cO2 would possibly be bad for.a.vegging plant..unless you do not want very rapid growth...the only problem I could imagine is.if you supplemented c02 in veg and didn't in flower. I have vegged 60 plants with c02 enrichment and had better end results than the 30 in the room next to Jr that had no enrichment.

I tend to turn off the fan on lights out, would it best to keep it going in the dark?

Here's what goes wrong with bad air flow, I learned in my first PC grow. Basically what happened is my plant started sending out leaves everywhere during flowering and it looked bad like it was choking and suffering. The leaves were deformed, looked like some other plant really. Once I got the exhaust back going the plant thankfully went back to flowering and it turned out good. Bad air flow or no air flow can totally fuck your whole grow up.