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A greenhouse won’t function as intended without ventilation. Airflow might not seem like much, but it’s critical for plant growth. Different methods are also used, and all play a part in improving the grow space’s efficiency.
In this guide, we’ll walk you through the importance of greenhouse ventilation. We’ve also included options to help you find what best suits your cultivation needs.
Why Greenhouse Ventilation Matters
A greenhouse takes the guesswork out of growing by managing conditions that normally vary outdoors. Inside, the environment is controlled, which makes it easier to grow well. This, however, can go off balance without proper ventilation.
Good air movement keeps temperature, humidity, and fresh circulation in check. Without it, heat and moisture can build up before you know it. That can lead to overheating, dampness, and stale conditions—none of which are good for plants.
Poor ventilation (worse, the lack of it) can also slow down growth or even cause damage. Not to mention, high humidity also creates the perfect setting for mould and disease.
Greenhouse ventilation helps prevent these problems. It’s not just a design feature, but it’s essential for keeping the growing conditions right inside.
What Ventilation Does in a Greenhouse
Greenhouse ventilation does wonders, starting with keeping the temperature steady. The inside can heat up quickly, especially in the summer.
Opening vents or using fans can help with this, allowing hot air to escape and letting cooler air in. This keeps the environment stable for your crops, in turn.
Constant airflow also stops too much humidity from building up. Plants, for one, release moisture into the air through transpiration. Excess moisture is removed, avoiding that heavy, muggy feeling inside.
Stagnant, damp air encourages mildew as well as aphids or fungus gnats, too. Keeping air moving makes it harder for them to settle in, cutting down the chances of a mould and pest outbreak.
Most importantly, fresh air brings in carbon dioxide, which plants need for photosynthesis. This also strengthens stems and keeps the growing environment balanced. That means healthier growth and better yields!
Different Ways to Ventilate Your Greenhouse
A greenhouse with built-in roof vents is a great solution. Simply open them to let the air flow and regulate temperature.
If roof vents aren’t an option, try these alternatives:
- Open the door and side panels: This helps release warm, stale air and lets in cooler, fresher air during the day.
- Use louvre windows: Tilt them to control airflow. They’re easy to adjust and don’t require extra installation.
- Install a fan (optional): If natural airflow isn’t enough, a plug-in fan can help. For smaller spaces, a 12–16 inch fan should suffice. Mount it opposite the door or low to the ground for better circulation.
- Add an exhaust system (optional): Electric fans fitted at one end of the greenhouse can pull warm air out. These are commonly used in larger setups but are also available in compact sizes for smaller spaces.
For more details, see our guide: How to Ventilate a Greenhouse.
The best time to ventilate
If you’re using vents, whether a built-in feature or the door, open them mid-morning. Close them in the late afternoon or early evening, before it gets too cool. In summer, you might leave them open all day, or even overnight if temps stay mild.
For circulation fans, do so during the day, especially when it’s warm or humid inside. You can leave them on all day if needed. But be sure to turn them off overnight if the air’s already cool and stable, to save power.
Exhaust systems can be turned on during the hottest part of the day. They’re most useful when inside temperatures rise above what your crops can handle. Stop them once it cools back to a safe level, usually late afternoon.
This next guide can give you more insights on greenhouse temperature – give it a read!
