Give your cannabis plants enough fresh air

Give your cannabis plants enough fresh air
Steven Voser

Find out why fresh air is so important when growing cannabis. Plus, we’ll also look at some basic ways for creating airflow.

There are many factors that affect how cannabis plants grow. The most popular concerns for growers usually involve light, humidity, and nutrients.

However, one often overlooked factor that can have a huge impact on your final harvest is air circulation.

In this article, we’re going to look at the importance of giving your cannabis plants fresh air. Plus, we’ll also look at some basic ways you can create airflow in your grow space.


Just like humans, plants need oxygen in order to survive.

During the day, plants will take in carbon dioxide from the air, water from their roots, and energy from the sun to produce sugar, a source of energy they can both consume and store. This process is called photosynthesis.

Whenever a plant doesn’t have access to enough sunlight it will consume the sugar it has produced in order to stay alive. However, in order to break down that sugar into a usable energy source, it also needs to consume oxygen.

While plants naturally produce oxygen when they synthesize, they also take in extra oxygen from the environment to help promote growth in areas that cannot photosynthesize (such as the roots of the plant). This process is called respiration.


In order for your plants to grow to their maximum potential, it’s vital they have constant access to fresh, oxygen-rich air.

Fresh air generally contains between 300-500 parts per million of carbon dioxide. The optimal conditions for cannabis plants is roughly 1,000-1,400 parts per million.

Now, in outdoor grow environments, this isn’t usually an issue, as air is constantly circulating. However, in an indoor environment, things can get a little tricky, especially if you’re growing multiple plants in a confined space.

That’s where air circulation comes in.

To ensure there is enough fresh, oxygen-rich air in your grow area, we recommend investing in a decent ventilation system that moves old air out of the environment and brings in fresh air from the outdoors.

Ventilation systems can be as simple as a few strategically placed fans or as sophisticated as an exhaust system. Which way you go depends on your preferences, budget, and how discreet you want (or need) to keep your grow operation. We’ll look at some of these different systems in more detail later on in this post.



Air circulation is a surefire way to ensure your cannabis plants have access to plenty of oxygen. However, that’s not the only reason why it’s important.

First of all, proper circulation is extremely important for minimizing the risk of bud rot and other conditions.

When plants respire, they produce water which usually builds up along the leaves and buds of cannabis plants. A build up of this moisture is one of the main causes of bud rot and other conditions such as mold and mildew.

Proper air circulation allows air to blow over and around your plants and helps to remove moisture, hence reducing the risk of the above conditions.

Air circulation also helps you protect your plants from garden pests like spider mites and fungus gnats. These pests have trouble living in well circulated areas and generally seek out areas with stagnant air.

Furthermore, the airflow will also help to dry out the top layer of your plants’ soil, which makes it harder for pests like gnats to breed.

By having air circulate throughout your grow area, you’re also help to keep humidity and temperatures steady throughout the entire environment. This is extremely important for larger grow ops, as stagnant conditions can create hot and humid pockets, which can affect the growth of individual plants.

Finally, exposing your plants to circulating air also helps them build up strong stems, which comes in handy when they start flowering and need to support the weight of the buds.



Fans are a relatively affordable and simple way to keep air moving around your grow area.

Ideally, you’ll want to keep air blowing both above and under the main canopy of your plants. Hence, we recommend one fan above your plants and one underneath the main canopy.

We also suggest using oscillating fans as they are cheap to run and can produce a nice, even breeze throughout a relatively wide area without blowing too much air on one single plant.

Once you’ve installed your fans, make sure you check your grow area to see that the breeze is steady throughout. Also, look out for signs of wind-burned leaves that are rolled and curved under so as to look “clawed.”


Exhaust systems are much more sophisticated than a simple fan system, but are also much more expensive to install and maintain. However, they allow you to remove old, stagnant air from your grow area and helps your plants grow to their full potential.

Exhausts are usually installed above the canopy of your plants as hot air rises to the top of the room. Many grow lights also come with exhaust extensions, allowing you to install the exhaust pipe right alongside your light.

The idea here is simple; while the fans in your room help to circulate fresh air, the exhaust pulls out any old air.

However, installing these systems is a lot more complex and requires a solid understanding of the airflow in your grow area. You’ll also need to calculate the necessary strength for your exhaust fan, especially if you're running a large grow op, and much more.

Steven Voser
Steven Voser

Steven is a long-time veteran of cannabis journalism, having delved into every aspect of the subject. His particular interests lie in cannabis culture, the emerging science of cannabis, and how it is shaping the legal landscape across the globe.