Most beginner indoor cannabis growers have enough on their mind to overlook the importance of adequate airflow in their grow rooms or tents. Nonetheless, effective ventilation is every bit as essential for great harvests as ample water and nutrition supply. This blog gives you ten top tips for proper cannabis ventilation.

The Importance Of Good Cannabis Ventilation

Many rookie growers don’t give grow room ventilation much thought. After all, their plants are getting enough water and light, and there’s always air in a room, isn’t there? Well, perhaps so; but an effective, adequate fresh air supply and sufficient circulation are vital for plants, including cannabis plants. Proper cannabis ventilation is an important means to improve control over room temperature and humidity.

That makes providing your plants with ample fresh air a top priority. They need it for photosynthesis, the process by which they derive energy from sunlight. To do so, plants need light, CO2, and water, which they then turn into sugars and oxygen. They can only do so in the constant presence of enough fresh air.

On top of this, plants can breathe using the stomata dotting the surface of their leaves. If the air in the room is not sufficiently refreshed, they won’t be able to breathe as they need to make full use of the CO2 they need for growth.

A final reason for ensuring optimal cannabis ventilation is the fact that warm, humid spaces are hotbeds for bacteria, mold, and pests. Most of these unwanted visitors prefer hot, damp air as their ideal habitat.

All in all, then, it makes perfect sense to consider the circulation, inlet, and exhaust of air in the room or tent you use for your indoor grows.

Cannabis Ventilation For Outdoor Growing

If you’re planning to grow weed outside, you’ll have all the fresh air that you could ever want at your disposal for free. Although cannabis plants have the same needs out on the balcony or in the garden as their indoor counterparts, they can use the wind to supply and refresh all the air they need.

For outdoor growers, cannabis ventilation should only become problematic if the wind picks up speed, since strong winds can easily snap and damage plants. Beyond that, it’s wise to pay extra attention towards the end of the outdoor season, as this is when moisture easily accumulates in flowering buds, with all the associated mold risks that brings. Here, finding your plants a nice and breezy spot can be helpful, as the natural airflow will help keep the interior of the colas dry and mold-free.

As you can see, cannabis ventilation issues can also occur outdoors. Nonetheless, the rest of this blog will focus on those planning to grow cannabis seeds inside.

Cannabis Ventilation: Controlling The Environment

Adequate cannabis ventilation improves your control over the moisture and temperature levels in your grow environment. The principle is very simple: you replace the old, stale air in the room or grow a tent by cool, fresh air drawn in from outside. It’s a necessity rather than luxury, really, as the air tends to grow too moist and too hot fast.

What you may not realize about the plants in your grow room or tent, is the fact that they have a natural tendency to perspire. They use the stomata on the leaves to release moisture to the environment. Evaporation of this moisture adds to the air humidity of the room.

On top of that, most people use high-powered grow lights for their indoor gardens. Although different types of lighting will emit different amounts of heat, any type will add to the room temperature while they are on. Proper cannabis ventilation will carry off heat as it expels air from the grow room, which helps keep temperatures at the required level.

10 Tips For Optimal Cannabis Ventilation

Providing the right cannabis ventilation equipment improves your control over your grow environment. It helps expel excess heat and moisture while allowing sufficient fresh air in. But what exactly is good cannabis ventilation, and how do you set it up? The 10 tips we provide below will help you determine the right airflow arrangements for any grow tent or indoor garden you want to manage.

Tip 1: Passive Or Active Inlet?

When setting up your tent or grow room, you’ll need to decide whether you prefer active or passive ventilation. Any growth requires a steady supply of fresh air, but you can arrange it either by passive or active ventilation.

Using a passive inlet means creating a natural airflow in the room without aid from mechanical ventilation. You can use windows or existing openings in the walls of your tent, without any need for electrical equipment. Of course, passive cannabis ventilation drastically limits your degree of control over the environment compared to active measures. We would not recommend it to dedicated growers anxious to squeeze everything out of their plants for maximum harvest results.

Active air inlets draw in fresh air by mechanical means using an inlet fan. This hugely increases the airflow in the room if used in the right way. If you have the means, an active cannabis ventilation setup is definitely the way to go.

Tip 2: The Exhaust Fan

Of course, any air you draw into your grow room has to be expelled at some point, too. That is where exhaust fans come in. As warm air tends to move upwards, exhaust fans tend to work best when installed in the top section of the room or tent.

When choosing your exhaust fan, the main aspect to consider is its capacity. The capacity of exhaust fans is expressed as CFM, or Cubic Feet per Minute. A bit of mathematics will help you determine the CFM airflow value required for your particular grow room or tent, as our next tip will show you.

Tip 3: Fan Capacity (CFM)

Calculating required exhaust fan capacity is based on grow room volume, expressed in cubic feet. Measure the height, width, and depth of your room or tent, and then use the example below to calculate your required cannabis ventilation CFM.

Example: The total volume of a tent measuring 6’ x 3’ x 3’ equals 54 square feet.

Ideally, you’ll want to refresh all air inside the tent once every three minutes. That is why you have to divide the total tent volume by three: 54/3 = 18.

CFM for cannabis ventilation = Volume ((in ft³) / 3

For this particular setup, exhaust fan capacity should be at least 18 CFM. This is the minimum capacity for adequate cannabis ventilation; don’t aim below this capacity, because there is a real chance your air refresh rate becomes insufficient.

You’ll notice your overall cannabis ventilation capacity is too high if the walls of your tent get ‘sucked in’ ever so slightly. A bit of negative pressure is fine, but don’t overdo it by going all in with an industrial capacity cannabis ventilation system.

Tip 4: Carbon Filters

Our next recommendation is to always install a carbon filter. They help remove contaminants from the air, but more importantly, they will help reduce the tell-tale smell of your cannabis plants caused by the terpenes they produce. You will be doing yourself, your family, and your neighbors a real favor. Carbon filters are usually fitted onto the exhaust section of your cannabis ventilation system.

Tip 5: Oscillating Or Swivel Fans

Choosing an oscillating or swivel type fan allows you to make full use of its cannabis ventilation capacity. These fans can rotate in two directions, creating varied airflow patterns that improve circulation throughout the room. They also have the added benefit of promoting development of sturdy stems and branches by mimicking the effect of a gentle breeze.

Tip 6: Cannabis Ventilation Inside Or Outside Of The Tent?

Generally speaking, your best option is usually to install your exhaust fan and other cannabis ventilation components on the inside of your grow room or tent. It will help keep any noise down to a minimum. If you have minimal space available, however, you could also try and set your gear up outside the tent.

Tip 7: Techniques & Tricks

In addition to all the technology you can use for optimal cannabis ventilation, you also have several grow techniques at your disposal that can help improve air circulation. Many techniques used for optimal light distribution will also promote better airflow. Examples include Screen Of Green and Low Stress Training techniques, which you can explore alongside many other useful techniques and tricks in our Grow Blogs section.

Making The Most Of Cannabis Ventilation

Our final three tips cover the best ways of installing and applying the cannabis ventilation measures and equipment you choose. The main thing here is to make sure air circulation resembles natural outdoor conditions as closely as possible.

Tip 8: Keep Things Moving

Out in the wild, cannabis plants are meant to spend their days gently swaying in the breeze. That is why you should always try to keep your plant in motion – but please be gentle or you risk damaging your crop.

Leave your cannabis ventilation on 24/7, but make sure to keep the leaves fluttering gently rather than blowing them all over the room. If the leaves move around too much, your plants will have a hard time positioning these ‘solar panels’ in the most beneficial way, which impairs their ability to make full use of the available light to grow.

Tip 9: Channel Your Airflow

Optimal leaf motion is easiest to manage by directing the airflow past your plants, instead of blowing them straight in the face. This provides sufficient cannabis ventilation capacity and variation without stressing out your grow with gale-force weather conditions.

Top 10: Horizontal Entry, Vertical Exit

Aim the airflow of your cannabis ventilation inlet horizontally. Make sure the flow remains at the level of the canopy and buds, without aiming the fan directly at the plants if at all possible.

As mentioned, the best position for your exhaust system is in the top section of your tent or room. This will allow the CO2 to flow along the entire plant. Grow rooms are warm by default, and since hot air rises, it makes intuitive sense to place your exhaust fan up high where all the not-so-fresh air tends to end up.

Reaping The Rewards Of Good Cannabis Ventilation

As you can see, proper cannabis ventilation is essential for any growth. Fortunately, a steady supply of fresh air is not that hard to manage. You don’t need to throw money at expensive professional ventilation systems. The level of complexity and the costs are entirely up to you to decide.

Even just opening the windows a few times every day will provide your plants with more fresh air. However, if you are looking to improve your control over your grow environment, a proper cannabis ventilation setup is your best choice. Ultimately, the best cannabis seeds in the world deserve the best growing environment you can provide, to ensure optimum growing, flowering, and harvest results.