How to Ventilate a Grow Tent

How To Ventilate A Grow Tent featured photo

Plants naturally thrive outdoors. But if you’re growing sensitive plants like cannabis, the unpredictability and fluctuations outside might be less than ideal. A grow tent offers a solution but something that easily passes over people’s heads is how to ventilate a grow tent.

When setting up a ventilation system, remember five key components: exhaust, intake, circulation, filter, and ducts. Before installing anything, choose and size the equipment you need. Then, install the exhaust fan and filter together. Opposite them is the intake fan. Lastly, position and install your circulation fans in place.

There are other considerations to think over when installing your grow tent’s ventilation system. There’s the choice of passive vs active setup plus the consideration of your grow room’s size.

Below, we’ll go over the basic steps of ventilating a grow tent, what materials you’ll need, and why exactly you should ventilate your indoor grow space.

What is Grow Tent Ventilation System?

Previously, we’ve talked about the importance of insulation to grow tents and grow rooms. Proper insulation helps your grow tent to keep the heat in, which plants need to flourish.

In this guide, we’ll talk about why you need to ensure proper ventilation in your grow space.

When growing plants outdoors, mother nature provides a natural breeze. Temperature and humidity levels also naturally occur. When grown outdoors, plants get the carbon dioxide (CO2) levels they need to grow.

The moment you decide to grow your plants indoors, in grow tents or grow rooms, you are in charge of the plant’s growing conditions.

Proper ventilation in your grow tent means providing ideal temperature, humidity, air circulation, and CO2 levels.

How much ventilation and fresh air does my grow tent need?

Asking how much ventilation your grow tent needs is the same thing as asking how often you should replace the air in the grow tent.

Most professional and experienced cannabis growers like to agree that replacing used stale air with fresh outdoor air once every minute is the best option.

Sticking with this figure provides the proper growing environment, which will give you the best yield come harvest season.

Why Do You Need to Ventilate Your Grow Tent or Grow Room?

If you’re still not convinced you should keep a proper ventilation system in your grow tent or grow room, we’ll go over below why exactly you should:

Keep ideal CO2 levels

Carbon dioxide is part of a plant’s nutrient cycle. It’s the food they eat for photosynthesis and for healthy growth.

An outdoor growing environment provides more than enough CO2 levels plants need to survive. When situated in indoor growing spaces, CO2 levels will quickly and gradually decrease throughout the day.

With very low levels of CO2 in your grow tent, your plant will not get the nutrients it needs and this will impede proper growth and development.

By providing proper air ventilation in and out of your grow tent, you can keep CO2 levels at an ideal level for your plant’s needs.

Remove excess heat

Cannabis plants thrive in an environment with an ideal temperature range of 70°F to 85°F.

Ideal temperature levels allow better plant yields. Cannabis plants, like most plants, don’t do well in a too-hot environment.

Unfortunately, the necessary grow lights could emit too much heat into your grow tent. Keeping a well-ventilated tent interior will help you remove this excess heat, keeping your plants healthy.

Control humidity levels

An indoor growing system needs to constantly keep relative humidity levels in check.

As we all know, plants vaporize water throughout the day. This means they can cause increased humid air in your indoor growing tent.

An increase in humidity levels will make your growing space susceptible to mold and mildew. These can be notorious to your plant’s growth and development. If left untreated, it can kill your plants.

Prevent pest infiltration and plant diseases

Hot and humid environments attract pests and insects. Keeping improper ventilation in your grow tent makes it susceptible to infestations. These can feed on your plants or introduce a variety of plant diseases.

Cover up smell

Lastly, a proper ventilation system for your grow tent could easily seal off and mask the smell of whatever plant you’re growing.

This is especially important if you’re growing cannabis in your home and would like to get prying eyes off them or just to keep the scent out of your home’s common spaces. Covering up cannabis scent allows you to discreetly and privately enjoy your hobby.

How to Ventilate a Grow Tent: The Essential Components

Next, we’ll go over in detail what essential ventilation components you should start looking into:

Exhaust fan or extractor fan for grow tent

One of the most basic but also one of the most important components for ventilation is the exhaust or extractor fan.

This is responsible for exhausting, venting, and expelling used stale air, excess heat and humidity, and odor from your indoor growing space.

You could actually get away with only an inline duct fan in your grow room ventilation system. However, using only will not give you the best results.

This fan blowing air out is typically ducted out to your window, bringing emissions right outside your home.

Intake fan for grow tent

On the other end of the spectrum and the opposite of the exhaust fan is the intake fan.

What an intake fan does is bring in the fresh air, replacing the used stale and stagnant air the exhaust fan gets rid of. This is essential to an effective ventilation system as it brings in the necessary CO2 gasses plants need to survive.

It’s important to know that there are two ways to bring new air into your grow tent ventilation setup:

  • The active setup

The active intake setup utilizes an intake fan to draw in fresh air into the growing space. This entails installing one fan to exhaust used air and then another to bring fresh air in.

  • The passive setup

An intake fan isn’t actually necessary for a grow tent ventilation to work. Some home growers opt for the passive intake setup instead.

The passive setup relies on both passive airflow and negative pressure instead of an actual physical intake fan. In the grow tent, there is an intake hole where new air passively and naturally enters.

To make the passive setup work, you have to ensure that the intake hole is three to four times larger than the exhaust hole. This setup can also have more than one passive intake hole.

Circulation fan (oscillating fan or clip fan) for grow tent

A circulation fan in your grow tent or room keeps the air moving around the entire growing environment. This creates air movement and makes your plants “dance”.

When air makes them move around a bit, this makes the plants and their stems stronger. Plants with strong stems don’t bow down.

These serve another important function: to cool down plants that are getting too hot.

Two popular options to circulate air are oscillating fans or clip fans.

Oscillating fans move side to side, covering as much area as they possibly can, as opposed to stationary fans. Clip fans are fans you can easily clip to a stationary surface to save space.

Carbon filter for grow tent

Carbon filters are what you will need in your ventilation system if you want to get rid of any odor or smell coming from the plant inside your grow tent.

When the exhaust fan draws out used stale air, it will first pass through the carbon filter. This filter will work to get all the smell and odor out before venting the air out.

A carbon filter set up with your exhaust will offer discretion and will get rid of the smell of cannabis before the used air gets out.

Ducts and pipes for grow tent

In some ventilation systems, you might need to connect your equipment together with ducting and pipes.

If your system is small, you might find yourself getting away with directly connecting all parts together. But if your system won’t allow a direct connection, using different ducts, vents, and pipes might be more efficient.

How to Set Up Grow Tent Ventilation

Keeping in mind all the essential components we’ve discussed above, let’s go over exactly how to set up your grow ventilation system:

  1. Choose and size your equipment

To start the actual installation process, the first thing you need to do is get the size of your exhaust fan. To determine what fan size you should get, calculate the size of your grow tent. From there, you can calculate the CFM, or cubic feet per minute, your space requires.

It’s highly suggested to oversize your fan to increase efficiency and help you save on utility bills.

Once you’ve figured out the size of your exhaust fan, get an intake fan that’s 20% to 30% less powerful. On the other hand, the size of your carbon filter should match the exhaust fan.

  1. Install the exhaust and intake fans and the carbon filter

Your exhaust fan and carbon filter are installed side by side. Place them up on the ceiling of your grow tent.

Next, your intake fan should be placed on the opposite side – across the exhaust fan and on the bottom. This positioning will ensure that air moves from the bottom to the top, covering all areas of the grow tent.

  1. Install and position your circulation fans

Lastly, install your circulation fans. While smaller grow tents can get away with just one circulation fan, larger setups may need at least two.

How to Cool Grow Tent: Consider Air Conditioning for Grow Tent

A real modern way to deal with heat and humidity in your grow tent is with an air conditioning unit. This is an especially smart investment if you live somewhere with very hot and humid climates, particularly in the summer.

Many home growers with larger indoor grow spaces opt to make this investment so their plants can enjoy the cooler breeze and in return, they can enjoy consistent abundant yields.

For this, you only have to make sure that the AC’s BTU output matches the size of your grow tent well, otherwise, all the effort and investment will be in vain.


Mother nature offers a growing environment for a variety of plants. But because it’s nature, it can be unpredictable. One way to counter this is by utilizing a grow tent instead, but what many indoor home growers don’t realize is the importance of a proper ventilation system.

To ventilate a grow tent, you have to keep in mind five essential components: exhaust fan, intake fan, circulation fan, carbon filter, and ducts and pipes. Before the installation itself, you should first size and choose your equipment accordingly. Then, install your exhaust and intake fans and your carbon filter. Lastly, install your circulation fans and you’re good to go.

Hopefully this has helped you learn how to ventilate a grow tent. You can reach out to us below with any more questions you may have.

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