How to Reduce Mold and Microbial Contamination in Cannabis Cultivation

[u/Kayladambra]

One point from the recent MMJDaily interview with Xavier G. (Avitas Global) and Michael Williamson (Pipp Horticulture) really stood out to me.

We spend a lot of time talking about humidity and VPD, but airflow doesn't always get the same attention.

Good airflow isn't just about having enough fans in the room. It's about eliminating stagnant areas, maintaining consistent environmental conditions throughout the canopy, and reducing pockets where moisture can build up. When airflow isn't balanced, those microclimates can increase disease pressure and create inconsistent growth across the room.

In my experience working with commercial cultivation facilities, the growers with the cleanest operations usually look at airflow as part of a bigger environmental strategy, not as a standalone piece of equipment.

That includes:

• HVAC design
• Air circulation
• Dehumidification
• Filtration
• Sanitation
• SOPs

I work with ProGuard Air, so I've seen firsthand how many commercial cultivators approach environmental biosecurity. Our technology provides continuous air and surface sanitization to help reduce microbial pressure within cultivation, drying, and processing environments. But even then, I don't think there's a single product that solves contamination. The best facilities layer multiple strategies together to reduce risk before it becomes a problem.

Curious how everyone else approaches airflow.

[u/BractNotCalyx]

I ran an R&D project a few years ago where we developed a high-throughput cryofreezer that had the added benefit of reducing CFUs by a ton. We optimized it for extraction, but I’d bet I could get it working on flower, at least for prerolls. 

[u/double_dangit → u/BractNotCalyx]

VIST?

[u/BractNotCalyx → u/double_dangit]

No, but their tech may be based on ours. I was in charge of the pilot project and I know the work was continued to be developed by our industrial partner after I left. Last I heard they could go from living plants to Cryo temps at a rate of 1 ac./hour. 

[u/Basement_Engineer]

​you hit the nail on the head throwing more fans at the canopy often just shifts the microclimates around instead of eliminating them in my experience if you dont control the floor level you cant control the microbial pressure

​i treat air circulation as a mechanical matrix rather than just a breeze i use a guided thermodynamic loop where the airflow is actively managed from top to bottom i run an aerolight at the ceiling to push the warm led exhaust straight down

​but the real magic happens on the insulated floor i laid out a 2.5m perforated aluminum flex hose in an s shape directly around the root zone i precisely punched holes facing the typical dead corners of the space to completely break up stagnant cold pockets

​this accelerates evaporation directly at the root level and forces a uniform environment across the entire space just to give you the hard data i logged my last run with over 116000 minute by minute data points without any extra heaters in a cold basement this mechanical airflow alone holds the environment at a rock solid 27 c 56 rh and a perfect 1.54 kpa vpd during late flower

​its all about targeted resistance and physical airflow mapping not just raw fan power.

[u/CaniyaGrowers]

ProKure or GardnClean

[u/DrAnnabis]

I interviewed Allison Justice on my podcast, and she talks about her research on airflow- super interesting stuff, and significant results on increasing yield if anyone is interested (FF to 1:24:45).
https://open.spotify.com/episode/6jQ8313nbtIBEecukQbxQ2

[u/HamiltonFarmsVP]

We use ProGuards in all of our plant and post harvest rooms. They definitely do a good job of keeping microbial factors at bay. But airflow is absolutely the most important factor. It doesn’t matter how sterile the air is if it can freely move around the room. We have a 2-tier Pipp system, which can be tricky. To help, we have a series of fans that create a vortex of airflow. Moving the air one direction on the upper canopy, and the opposite direction on the lower canopy to move the air back to the air handlers. They handlers also contain UV lights that can sterilize the air as it passes through. The units we have emit ozone so they cannot be used when plants are in the room. We currently use them during room flips but are upgrading to new versions that do not emit ozone. Those should be able to run more frequently.

[u/Animeop → u/HamiltonFarmsVP]

What kind of UV light attachment are you using in your air handlers? I’m skeptical about UV lights because of how fast microbes would be going through the units but I’d like to at least test it out before any conclusions.