Importance of Airflow for Indoor Growing

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Airflow is one of the forgotten environmental factors of indoor growing. But is not any less important as you need to take advantage of the ability to control it and make optimum growing conditions. If you don’t, you can have decreased yields, disease problems, and other issues.  

Basic Reasoning:

In mother nature, airflow is naturally occurring caused by weather patterns thru wind and atmospheric conditions. Winds keep air moving and mixing which is important to a plant’s health. This keeps oxygen & CO2 levels mixed, humidity evenly distributed, and etc. This allows plants to get their natural needs to complete photosynthesis most efficiently.


Humidity is the level of moisture trapped in the air. It is caused by plants transpiring, bodies of water, and much more. If it is too low, it will dry out plants encouraging them to transpire too much. If it is too high, it can encourage the development of plant diseases. 

CO2 Levels

CO2 is a basic need for plants to complete photosynthesis in their leaves to feed themselves. With stagnate air, levels of CO2 can fall not and lower CO2 uptake. Less food production means less vegetative growth and weaker crop yields for fruiting plants.   

Temperature Control

If the air is not constantly mixing, hot spots can form. You can see this when you add cold water to a hot bath. It creates cold spots till it mixes. This stress can cause issues with growth. Air movement mixing temperature variations quicker than stagnate air. 

Purely Movement

“Wind” encourages plants to strengthen their growth so they don’t break under their own wieght. Strong growth prepares fruiting plants to bare the weight of their fruit and/or flowers.  

Simulating Mother Nature

Controlling this environmental factor is actually pretty easy. For indoor growing, it is completed with different types of fans for different purposes. Depending on the size of your growing environment, sizing can sometimes take some trial and error. 

Intake Fans

Intake fans pull in air to the growing space from outside. They are usually in-line fans type. This brings in fresh air from the outside and important for bringing in CO2 created by the outside world. Also, they are vital for bringing in cooler air. 

Exhaust Fans

Mars Hydro 2'X2' Grow Tent Kit

Exhaust fans are normally inline-type fans similar to intake fans. These fans exhaust out hot air, excess O2, and excess humidity. Many times people will also have carbon filters so the air does not smell especially if the outside is a living space.

These fans are just as important or more important than Intake fans for the tasks they do. Smaller grow environments can actually have only exhaust fans. The actions of sucking the air out of the grow space will create “negative air pressure.” This will cause air from the outside to be pulled in without an intake fan. 

Internal Circulation Fans

oscillating fan for grow room

Circulation fans are what you normally think of as an “osculating cage fan” for staying cool. They are very important for mixing the air in larger grow environments such as grow rooms and greenhouses. They also simulate wind to encourage stronger plant growth.


Airflow is a very important often overlooked environmental factor. You can start through trial and error OR many professional growers will run calculations on “air volume” in the grow space to size fan systems. Its control is very inexpensive compared to its importance for increasing yields and plant health. Check out our General Environmental Factors Post! (Click here)

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