EN FR
Vegetable Illustration

How To Properly Ventilate Your Greenhouse and Why this is Essential in Your Success

Greenhouse management

Without a doubt, proper airflow and ventilation in a greenhouse are indispensable for any greenhouse success story. Having proper airflow helps prevent sickness, control the climate and reduce humidity pockets in your greenhouse. Your human senses might not notice that there are microclimates in your greenhouse as humid air condenses near your plants leaves as they give off moisture during their respiration.

As we know, stagnant air sometimes carries sickness, and though we love our plants through sickness and health, we would prefer them to be healthy. Not to mention, having any condensation buildup is a nightmare for any greenhouse grower. Learn more on how to properly ventilate your greenhouse and why this is essential in your success.

Natural Airflow

Even though most modern greenhouses are equipped with sides that roll up either manually or automatically, it would be foolish to rely only on side roll-ups for airflow. If your greenhouse is smaller than 30 feet maybe you could get away with that option, but you would certainly not be optimizing your climate and plant health. Additionally, you would really need to consider your greenhouse placement so that there is wind; the roll-ups are only so good if there is wind! If the day is stagnant and humid, the inside of the greenhouse will be as well. It is an unpredictable ventilation system.

If you are keen on only using natural airflow, you should contemplate the pros and cons of installing an opening roof. This is one of the ways to properly ventilate your greenhouse to optimize your production and success. The roll-ups will allow air into the greenhouse and the hot air will rise and go out through the open roof.  We should mention though that if you were to install an opening roof on your greenhouse, you will need to have it installed professionally which comes at a higher cost.

Properly ventilate your greenhouse with only natural airflow can be challenging. / Credit : Alex Chabot
Properly ventilate your greenhouse with only natural airflow can be challenging. / Credit : Alex Chabot

Mechanical Airflow for Ventilation Optimization

Combining natural airflow from the wind outside coming in through sides of the greenhouse as well as mechanical airflow that ensures even air distribution, is the winning ticket. Without adding much cost, horizontal airflow fans (HAF) are an awesome accessory for your greenhouse climate and a great tool to properly ventilate your greenhouse. They are called like this because they are installed parallel to the crop rows and push air horizontally. They simply force the air through the greenhouse, evenly distributing it.

If you live in a climate with hot summers you could consider the installation of a positive pressure ventilation system. It will draw the cool air from outside into the greenhouse and distribute the air through a large perforated plastic tube on the ceiling of the greenhouse. Positive pressure ventilation is also a cool option if your greenhouse is surrounded by other buildings or has some sort of windshield that reduces the natural airflow.

Positive ventilation can also be a good ally to properly ventilate your greenhouse during cold months. During the sunny days of winter, it is preferable to ventilate with this system than with the roll-ups. It allows the hot greenhouse air to mix with the cool outdoor air before it reaches the plants. You just need not to overdo it.

Positive ventilation can properly ventilate a greenhouse during cold months. /Credit : Alex Chabot
Positive ventilation can properly ventilate a greenhouse during cold months. /Credit : Alex Chabot

So, what should I do?

If you’re tight on cash, we would recommend installing a greenhouse in a cleared area with enough access to wind, and a non-opening roof. Make sure you have roll-ups on the side, whether they be automatic or manual. You should definitely install HAF fans throughout the greenhouse to have decent airflow. This is a totally acceptable ventilation system. 

If you’re not so tight on cash, we would recommend optimizing your system to properly ventilate your greenhouse by having automated roll-ups on the sides and HAF fans. You could choose between an opening roof vent or a positive pressure ventilation system depending on the money left. The roof is pricier but more efficient and the positive pressure ventilation is cheaper but less efficient.

Want to learn more before making any decisions regarding your greenhouse?

We have prepared a series of articles that will help you expand your knowledge on the topic of greenhouse installation so that this endeavour can be more enjoyable and less overwhelming.

We invite you to check out the following articles: 

If you need any further resources to help you with your greenhouse production or to learn about best practices for operating a profitable farm, we invite you to join the Market Gardener Masterclass. The Market Gardener Masterclass is a comprehensive online course that documents all the steps of successful market garden production. Our method has been developed based on over 20 years of experience in organic market gardening and is designed to allow you to deliver consistent results that will guarantee the success of your farm