Cannabis Ventilation: Why you Need it & How to Set it Up

Seeds, lights and... fans?

Cannabis ventilation is often overlooked.

The very basics of plant science tell us that plants rely on the ability to absorb CO2 (carbon dioxide) to grow.

In turn releasing oxygen back into the atmosphere.

Plants also need ideal humidity levels to stay healthy and thrive.

As such, the grower will want to ensure that they take proper steps to ensure their plants are getting the fresh air they need.

Here we will explore the importance of ventilation and ways they can set up a grow room with ventilation or add ventilation to existing spaces.

The Importance of Cannabis Ventilation

Cannabis ventilation involves techniques the grower will use to ensure the adequate amount of air is hitting their plants.

  • Temperature Control

Ventilation also ensures that the temperature in the grow room is being kept at a cool enough temperature for the strain to be able to grow comfortably.

If your plant is kept in an environment that is too hot, it can severely negatively affect your plants.

  • Humidity Control

Avoiding mold and mildew is also an important reason for ventilation.

Humidity that's too high can cause mold and mildew on your plant, which can lead to pathogenic infection in your plant and destroy your crop.

  • Plant Breath-ability & Toxin Control

Your plant also needs to breathe to stay healthy, as it goes through transpiration, it will release any toxins through its pores.

Having consistent air flow will ensure that toxins are getting cleared away from your plants.

Also, they'll be able to maintain a toxin-free grow environment.

  • Odor Control

Ventilation also helps manage the odor of your plants.

It reduces the overall pungent smell that could crop up in your grow space.

Setting Up Ventilation in Your Grow Room

There are several ways that you can set up your grow room to be conscious of ventilation.

And no shortage of ways to enhance your current grow room to encourage more ventilation.

Cutting a Hole in Grow Your Grow Room?

When the grow area permits, some growers choose to cut a hole in the top of their growing space to allow for ventilation.

Whether this is at the top of a closet door, or a cabinet that you’re growing in, a small hole will allow heat to escape.

Leaving Door Ajar

When it’s not possible to cut a hole at the top of your grow space, many choose to leave the door to their grow space slightly ajar.

Some opt to cover most of the space with tape or another sealant to limit the size of the ventilation space.

Setting up an Exhaust Fan

Depending on the size of your grow room, your exhaust fan doesn’t need to be huge.

Instead, scale it up or down to your grow space.

An exhaust fan, should be set to pull air out of your grow space.

This will help regulate the temperature of the room so the plants can comfortably grow.

You’ll also want to ensure you understand the heat your lights are putting out—this will also be a factor for exhaust fan size.

To test the effectiveness of your exhaust fan, you’ll want to ensure you’re testing the temperature of your space.

A suggested comfortable range for plants is between 70 and 85° F with lights on, and between 58 and 70° F when lights are off.

Use Lights with Built in Cooling Fans

Since your lighting can seriously affect the temperature in your room, you may opt for lights with cooling hoods.

This lighting feature will take away the excess heat from the light source.

Ensure it doesn’t change the temperature of your plant’s grow room too much.

Using Regular Fans

You need a regular movement of air in your grow space, and fans provide a cheap and efficient way to do this.

Having an oscillating fan will ensure that the air is getting stirred up regularly and that there are not hot spots being created from the lights.

Many choose to mount a small fan on the wall, or will just choose a standing fan—either one works fine.

Depending on the size of your grow space, you may want two or more.

Something to be extremely conscious of is the force of air that your fans are giving off.

You simply want to be stirring the air around in your grow space.

You don’t want to blow your plants over or risk them breaking with too strong of a wind.

Ducting and Carbon Filters

For those who are looking to add an element of sophistication and a more controlled ventilation process, they may be interested in looking into ducting.

This video, provided by grower, Grow420Guide, shows how to install a ducting system in a growing tent in this video:

Adding a carbon filter to your ventilation system will also help to minimize odors coming from your grow space.

Use Dehumidifiers to Take Control

Depending on where you live, and the natural climate of your grow room, you may need additional measures to decrease humidity.

Having a humidity gauge in your grow room will allow you to monitor your humidity levels and ensure they’re not getting too high for the stage of growth.

Humidity levels should stay between 50% and 70% in the vegetative state, and between 50% and 60% during the flowering stage.

If you’re finding that you’re not reaching the ideal humidity levels, a small dehumidifier set up in your space (pointing outwards) will ensure that the excess moisture is taken out of the air.

This works in reverse as well if you live in a dry climate.

A humidifier can be added to your grow room to bring  the levels up to the 50-70%.​

Let it Flow

As we’ve demonstrated, air flow and ensuring that your grow space's temperature and humidity are controlled will make sure you’re growing your plants in a healthy environment.

By carefully considering your grow space, the number of plants you’re growing and the available resources, you should be able to find all you need for cannabis ventilation within your home.

Remember, ventilation can make all the difference in your plants!

Tony Hand

Founder & Editor-in-Chief of If he's not smoking or watching anime, you can find him yelling at over play calling.

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