The Importance of Air Circulation

There are many diseases and pest around that can find their way into your grow room and cause total havoc and destruction. Each has their own prevention and control options, but there is nothing more universal for nearly all disease and pest infestations as adequate air circulation.



Insects are small, and usually very poor flyers. They are required to maneuver around your plants in search for the best spot to set down and begin reproducing. With strong air currents, this can be quite a challenge to do, and in many cases make it impossible to stop and begin reproducing. Air circulation in the growroom is one of the most effective ways of keeping insect populations down, by simply making it nearly impossible to maneuver around effectively, and begin laying eggs.


Plant Disease

Diseases like fungal or bacterial infection is another infection easily controlled with simple airflow. Fungal spores such as powdery mildew need to set down on a leaf surface and have time to begin growing and infecting the leaf surface. With the air always moving around and blowing on the leaves of your plants, these powdery mildew (or other fungi) spores will never have the opportunity to grow and develop into a full on infection.


Plant Growth

Even the health and strength of your plants can be affected by the air movement in the grow room. In nature air movement is constantly pulling and pushing on the leaves of trees and outdoor plants. In the grow room this can be mimicked through the use of circulation fans. These fans push on the leaves and stalks of your plants it causes them to grow thicker and stronger. This allows them to withstand more stress in the future, and strengthens the stalks that are going to eventually hold flowers or heavy fruit.


Smaller Grow Rooms

In a small grow room such as a grow tent, air circulation can be as simple as an adequately sized extraction fan. If the right size is used, it will allow air to flow out at a steady enough rate to keep the air moving inside the grow room. The addition of small circulation fans is also recommended however.


Larger grow Rooms

In larger grow rooms, it is necessary to add circulation fans to the room in order to make sure air is flowing through all sections of the grow room including the undersides of your plants leaves and root zone. Ensuring adequate extraction is also necessary and prevents the buildup of stale, air in the grow room.


How to Ensure Adequate Air Movement in the Grow Room

Although every grow room is different, there are some basic methods of ensuring the air circulation is adequate in any grow room.

For starters, having a look at the leaf movement in your room can tell you a lot about how the air is circulating. Look at the leaf movement. You want the leaves to rustle gently throughout the room, but you don't want them to be nearly blowing straight off the plant either. There can definitely be too much of a good thing with regards to air circulation.


Extraction Fan:

For exhaust or extraction fans, you will want to place it higher up in your room in order to remove the hot air that has accumulated in the top portions of your grow room. Some growers like to place the extraction at the bottom however if they live in a naturally cold area and wish to keep this hot air within the grow room. IUt does not matter what you do for this step, but it does make a difference on where you place your intake fan.


Intake Fan

The intake fan should go on the opposite side of the growroom than the extraction fan. In most cases, with the extraction occurring from the top of the growroom, the intake should be located at the bottom and as far away from the extraction as possible. This makes all of the air flow through the grow room and can add significant air circulation even before adding the circulating fans.


Circulation Fans

When adding circulation fans, you want to place them so that they “mix” or “chop” up the air in the room. Plaing them in all the corners of the room, and angling them to create a tornado type of motion is another good idea and allows the air to flow freely throughout the grow room. It is also important to remember the undersides of your plants leaves when placing circulation fans. Allow at least one circulation fan to aim the airflow directly under the leaves of your plants, to remove the stale air that is protected by the leaves and stems of your plants. It can also help alot to do some trimming on the bottom portions of your plants to allow this air to travel freely throughout your crop.