Do Greenhouse Need Ventilation?

Greenhouses require airflow. One of the most crucial aspects of a greenhouse is ventilation. The following are the key functions of a ventilation system in keeping plants healthy.

  • Controls the temperature.
  • Controls humidity.
  • Carbon dioxide is produced.

You now know how vital greenhouse ventilation is for optimum plant growth. Let’s take a deeper look at how they do it so you can figure out which ventilation system is best for your greenhouse.

Reasons Why Greenhouse Ventilation Is Important

Greenhouse ventilation is critical for more reasons than the ones I discussed at the start of this post. Here’s a rundown of how ventilation might help your plants stay healthy.

  • Temperature Regulator & Humidity controll
  • Carbon Dioxide (CO2) produced
  • Prevents pest
  • Aids in Pollination
  • Air Movement and Circulation

Ventilation Can Regulate Temperature and Control Humidity

Although humidity helps keep the soil balanced and the plants healthy, too much moisture can cause diseases to develop in warm spaces. Having a regular ventilation system and moving air will help keep the humidity in check.

Too much heat in a greenhouse can cause problems for your plants, especially during cooler weather. It can raise the temperature and threaten their health. A ventilation system can help remove the excess heat and keep the plants healthy.

Your greenhouse can also get humid if the water from your plants doesn’t get removed. This can cause high humidity.

While some plants do well with their humidity, others can quickly succumb to the harmful effects of a humid environment. This is because ventilation helps remove the moisture from the air and brings in drier air.

Getting rid of the weeds around your greenhouse can also help reduce the humidity in your environment. You can also use a thermometer to measure both temperature and humidity.

It’s important to note that both temperature and humidity are related. Having a good understanding of these two factors can help keep your plants and greenhouse in good health.

Ventilation Helps Create Carbon Dioxide

If you’re not intentionally supplying carbon dioxide, you’ll need ventilation in your greenhouse to allow your plants to flourish. This is done using a ventilation system.

To conduct photosynthesis, plants require carbon dioxide. This is how they convert carbon dioxide, water, and sunshine into glucose, which they require to live.

When the amount of carbon dioxide in the atmosphere declines, so does the rate of photosynthesis, and your plants don’t grow as well.

Ventilation Can Prevent Pest

A ventilation system can also assist keep typical greenhouse pests away from your plants. Pests thrive in warm, humid environments, therefore a ventilation system that controls temperature and humidity is essential.

Another strategy to keep pests at bay is to become familiar with the most common greenhouse pests so you can keep an eye out for them. Some of the most frequent greenhouse invaders are listed here.

  • Shore flies
  • Gnats
  • Thrips
  • Whiteflies
  • Slugs and snails
  • Leafminers
  • Mealybugs
  • Bloodworms
  • Two-spotted spider mites
  • Aphids
  • Cyclamen mites

Ventilation Helps in Pollination

Outside of a greenhouse, the environment takes care of pollination — a wind blows or a humming bee hops from flower to flower doing its job to pollinate. However, there is no wind inside a greenhouse.

A good ventilation system with fans shakes the plants and allows pollination to occur. If you discover that the plants in your greenhouse aren’t bearing fruit, you may have a pollination problem.

Ventilation Offer Air Movement and Circulation

Before buying a greenhouse, I suggest that you purchase a ventilation system that will be installed directly into the walls. For larger greenhouses, the exhaust fans should be installed on the roof as well as the perimeter base.

For instance, a polycarbonate greenhouse could be a money-saving option due to its ventilation system.

Having second thoughts about the importance of ventilation in a greenhouse? In this article, I will talk about the various reasons why it is important to have ventilation in a greenhouse.

A healthy greenhouse environment prevents plants from experiencing the harsh conditions of the environment, such as wind, rain, and ultraviolet radiation.

Air is one of the best ways to strengthen and protect plants. It can stimulate their natural defenses against disease and weakness.

In environments where there is little or no light, plants can get legged and spindly. Air movement helps them avoid this condition and maintain a healthy garden.

How to Keep Greenhouse Running Smoothly with Ventilation

Some people think that all they need to do is buy a greenhouse. However, in reality, there are plenty of factors that can keep their plants running smoothly.

The greenhouse is a structure that cannot do anything about the outside environment. This means that it will not be able to control the temperature inside.

The greenhouse can only protect its plants from the elements during the winter. However, it can’t provide adequate cooling and heating.

This is why it is important to look into the various components that can help the greenhouse keep its temperature at a reasonable level.

Types of Ventilation Systems for Greenhouses

Now that you’ve determined that a greenhouse ventilation system is required, you must decide what type of ventilation system you want to install. Natural and mechanical ventilation systems are the two most common forms.

Here’s a quick rundown of the fundamentals of both systems.

Natural VentilationMechanical Ventilation
Relies on windCan be automated
Less controlMore control
No powered fansUses fans
Relies on thermal buoyancySealed environment = no pests

Natural Ventilation

In a greenhouse, natural ventilation is achieved by using wind and thermal buoyancy. This method works by taking advantage of the natural ventilation of the air.

People who use natural buoyancy have vents on their roof. When the temperature gets too hot, the air rises and goes out the vents.

When the hot air from the roof vents goes out, a vacuum is created, which then brings in cooler air through the vents.

If you’re going for the natural ventilation route, then a solar powered vent opener might be beneficial. This device automatically opens the greenhouse’s ventilation system when the temperature rises.

Mechanical Ventilation

A mechanical ventilation system uses fans or other devices to circulate air in and out of your greenhouse. It can be controlled by you, so you can keep pests at bay and increase the efficiency of your greenhouse.

Which One to Choose

Deciding on the type of ventilation system that will work for your greenhouse depends on many factors. One of these is the cost. A natural ventilation system usually costs less than a mechanical one.

A natural ventilation system is ideal for homes with limited wind resistance. However, with a mechanical system, you can control its operation.

Using Your Ventilation System During Other Seasons

When using a greenhouse, it’s important to modify the ventilation system to accommodate the varying temperatures inside the facility. In the winter, you might need an outside heat source.

The difference in temperature can create humidity in the air. Generally, fans should be adjusted to three air changes per hour to avoid running too much.

If you want to achieve these rates, you can either buy a smaller fan or turn the dial down on your current one. In the winter and spring, your ventilation rate will gradually decrease, which means that you’ll need to use less of it to maintain a comfortable temperature.

Heating Options

Although it’s important to keep your greenhouse at a good temperature during winter, many plants can tolerate a daytime temperature of around 70 to 80 degrees Fahrenheit.

When it comes to growing plants in your greenhouse, the ideal temperatures can vary depending on the type of plant you’re growing.

50° Fahrenheit65° Fahrenheit70° Fahrenheit
Sweet Pea
African Violets
Tropical plants

Here are some of the several types of heaters you can use to heat your greenhouse.

  • Conventional fuel-based heaters
  • Electric space heaters
  • Portable space heaters
  • Oil-filled radiant heaters
  • Ceramic space heaters
  • Infrared space heaters

Conventional fuel-based heaters: Conventional fuel-based heaters are usually used for large greenhouses. They emit higher levels of greenhouse gases than wood or kerosene heaters.

Electric space heaters: Electric space heaters are more energy-efficient and are generally used for smaller greenhouse setups.

Portable space heaters: Portable space heaters are useful since they are lightweight and easy to transport to anywhere you need them.

Oil-filled radiant heaters: An oil-filled radiant heater uses electricity and oil to heat up your home. They’re also very energy-efficient, and they can be easily moved.

Ceramic space heaters: These space heaters use ceramic to heat up a small box. They’re energy efficient and are ideal for small greenhouses.

Infrared space heaters: In a greenhouse, infrared space heaters are used to heat up plants. The air inside the room warms the plants.

Cooling Options

In the warmer months, a ventilation system paired with additional cooling methods aids in maintaining the temperature of your greenhouse.

Here are a few cooling alternatives for your greenhouse.

  • Misting System
  • Fogger
  • Evaporative Cooler
  • Shade Covers

Misting System: A misting system does exactly what it says on the package. It emits a thin mist that evaporates, lowering the temperature in the greenhouse.

This technique does have a disadvantage in that the misted water may not always evaporate, resulting in greater humidity. A misting system, such as this one from Amazon, might suffice.

Fogger: A fogger works in the same way as a misting system does. It emits fog particles into the surroundings, where they linger until they evaporate. The particles it emits are typically slightly smaller than the water emitted by a misting system.

Evaporative Cooler: An evaporative cooler is a closed device that retains water inside a cooler and subsequently exhausts the cooled air into the greenhouse.

Shade Covers: Shade cloth is commonly used to keep greenhouses cool. A shade cover keeps some of the sun’s rays out of the greenhouse. This can lower the temperature by 20%. As you can see from these Amazon shade covers, this is a reasonably priced choice.


A strong ventilation system is essential for controlling all of the environmental conditions I just mentioned if you want to grow the greatest, most prolific plants possible. Whether you choose a natural ventilation system or a mechanical ventilation system will determine the size and location of your ventilation system.

Because of the temperature differential between outside and inside your greenhouse, humidity becomes an issue. After reviewing the various available heat sources, it is advisable to consider the space you need to heat as well as your budget when deciding on a heat source.

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