Ideal Oscillating fan placement in flower?

[Vintage1969]

Is it best to have the air blowing directly on the plants,
Or down low more on their stems- under the canopy, or is it best to have the air blowing over the tops of the plants? I've had problems in the past with fans causing windburn when blowing directly on the leaves.

I am running CO2 hope to have a high enough RH for the proper VPD. I want to make sure I have enough air movement, and No stagnant air spaces.

 

[OldGuyInOregon]

Well you have asked a good question. My two cents is that you just need to stir the air up for flowering plants, it is not like they are still building stems. I'd probably point that fan anywhere but at the plants.

If the plants were in veg, maybe a different answer.

 

[snake11]

Fans blowing on the plants tends to result in stronger plants in my opinion. Not hurricane strength or anything. Just a nice oscillating breeze.

 

[DoubleTripleOG]

I place oscillating fans so they move the air right above the tops of the plants. Another oscillating on the floor on low directly under the co2 burner, blowing the co2 into the undersides of the plants. Then usually have a fan pointed into one of the corners of the room. That makes the air really circulate thru the room.

Not to piss in your cheerios snake11, but fans blowing on plants tend to make plants transpire a lot faster than they like. Curled leaves and crispy dry is what usually happens over time.

 

[SoufLondon]

I have fans blowing cool air in the bottom at pot height (not really much hits directly onto the plants, more the pots) and extractors sucking hot air out at the top. Have never had any issues this way and i normally get strong enough plants that they dont need help supporting themsevles untill the last couple weeks of flower

 

[snake11]

I place oscillating fans so they move the air right above the tops of the plants. Another oscillating on the floor on low directly under the co2 burner, blowing the co2 into the undersides of the plants. Then usually have a fan pointed into one of the corners of the room. That makes the air really circulate thru the room.

Not to piss in your cheerios snake11, but fans blowing on plants tend to make plants transpire a lot faster than they like. Curled leaves and crispy dry is what usually happens over time.

I don't see any of that. Maybe you are using too much fan. A gentle oscillating breeze blowing has caused no stress or dry out that I have observed. I suppose there are a lot of other environmental conditions at play like where you live and if you do sealed room or air exchange.

 

[RedBeardy5]

Yeah if I have a fan blowing directly at the plants 24/7 they get stressed and the leaves droop and get dry. Secondary wind is better, blowing against a wall to diffuse the air.

 

[Dready_jake]

Ugh I dreaded finding this thread. There is so much misinformation about air movement and wind.

Firstly why when you are adding the most weight to the stems would you want to stop strength training them with fans? As weight builds and you knock it around a little with a fan the stem builds strength too making it require less support.(still typically need some support tho)

If you have low humidity then there can be too much wind as it causes transpiration to increase drying out the leaf. But that's ONLY in LOW humidity environments and you should humidify.

If the humidity is dialed(VPD says proper humidity is 75% in an80° room) then there can be as much wind as the plants can stand without falling over. In fact if you don't have ENOUGH fans you will get stagnant air and a chance for budrot/mold and mildews. But especially when trying to utilize VPD, every leaf must be moving.

That being said I prefer multiple and many fans from different angles. I got ones blowing Up across through the canopy and a couple hanging and blowing down like ceiling fans. I believe if you are doing it right there is never too much wind.

But if you don't have air flowing through the canopy and all leafs are moving, I'd give it a year before some bud rot or powdery mildew find a place to take hold. Blowing at the wall? What good does that do?

If you have good VPD don't listen to these guys. direct fans at the plants and just watch to make sure they're happy with it.

 

[Vintage1969]

Great thanks for the advice!

 

[RedBeardy5]

I'm going to try raising the humidity and put the fans blowing on them and see how it goes.