Greenhouse Dehumidification Basics: What Is the Ideal Humidity?

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If you have a greenhouse, you know it can be difficult to regulate temperature and humidity. High humidity levels can lead to several problems, which can prevent healthy plant growth. So we will teach you greenhouse dehumidification basics, including optimal humidity levels.

The ideal humidity for a greenhouse varies depending on the types of plants you are growing and the current season. But in general, a 50 percent to 70 percent humidity range is considered optimal for greenhouse plants. 

It is also important to understand that temperature and ventilation affect humidity levels. Below, we will cover the basics of greenhouse dehumidification. You will also learn about the different ways to control greenhouse humidity.

What Is Greenhouse Dehumidification?

What Is Greenhouse Dehumidification

Greenhouse dehumidification is the process of reducing humidity or moisture levels inside a greenhouse.

A greenhouse provides a controlled environment to help cultivate plants. Its environment is usually humid because of all the plants inside an enclosed structure.

This humidity is important for healthy plant growth. It helps plants soak up water and nutrients from the soil to help them flourish. Humidity also affects the photosynthesis rate. It is the process by which plants convert carbon dioxide, sunlight, and water into oxygen. 

However, excessive humidity levels can harm plants. Too much humidity and moisture can lead to mold growth, increased disease vulnerability, and reduced plant transpiration. That is why greenhouse dehumidification exists to regulate humidity levels.

Why Is It Important to Control Humidity?

You must maintain optimal humidity levels in your greenhouse for several reasons.

First, excessive humidity can increase the growth of mold, mildew, and fungi. These microorganisms can compromise the health of your plants.

High humidity can also prevent proper photosynthesis, nutrient absorption, and plant transpiration.

You can prevent all these problems by controlling humidity levels inside your greenhouse. You can also avert the spread of diseases that your plants may get due to moisture. You can ultimately create the ideal environment for your plants to grow healthy and resilient.

How Does Humidity Affect Plants?

Humidity can affect plants in different ways, depending on the moisture level present in the greenhouse.

High Humidity

Excessive humidity levels can reduce water intake and nutrient absorption. It can lead to stunted plant growth.

High humidity can also promote the growth of mold, pests, and fungal diseases. These can ultimately harm your plants if uncontrolled. 

Additionally, too much moisture in the air can hinder photosynthesis and gas exchange.

Low Humidity

Low humidity can also harm your plants. 

It can speed up transpiration, or the process in which plants lose water vapor through their leaves. It can lead to excessive water loss from the plant. It eventually causes wilting and leaf dehydration. 

Low humidity can also prevent plants from soaking up essential nutrients. It can result in nutrient imbalances and deficiencies. It ultimately increases susceptibility to diseases and pests.

What Is the Ideal Humidity for Greenhouse Plants?

As previously mentioned, having too much or too little humidity can harm your plants. So you must always maintain ideal humidity levels in your greenhouse.

Most greenhouse crops can thrive with a relative humidity range of 50 percent to 70 percent. However, newer plants require higher humidity levels of 70 percent and 85 percent to promote germination. As they mature, they need less moisture to prevent several issues.

You must also note that different plant species have unique humidity requirements. If you are unsure, you can contact agricultural experts to learn the optimal humidity range for a specific plant.

What Is the Ideal Temperature for Greenhouse Plants?

The temperature of the greenhouse can affect humidity levels and, in turn, plant health. 

Most vegetable plants usually thrive at around 80°F (27°C). Meanwhile, cold-season crops such as lettuce and greens only need 50°F (27°C).

You must also consider the outdoor temperature. Expect lower temperatures during nighttime. So it is best to adjust the indoor temperature of the greenhouse to ensure healthy plant growth.

Avoid setting the temperature too high or too low because it also leads to several problems in the future.

Finally, remember that specific plant types need different temperatures. Below are some general temperature guidelines for different plant species.

  • Fruiting Plants – They thrive in warm air temperatures around 75-85°F (24-29.5°C)
  • Herbs – These plants grow in temperatures between 60 and 85°F (15.5-29.5°C)
  • Leafy Greens – They prefer cool temperatures of 60-70°F (15.5-21°C)

How to Control Humidity?

Below are three ways to control humidity in greenhouses.  

Use Natural Ventilation to Increase Air Circulation

One of the best methods to maintain humidity levels is using ventilation. It can be as simple as opening windows, doors, and vents to prevent moisture buildup. Doing these also allows fresh air to circulate, ultimately reducing humidity in a greenhouse.

You can also use fans to increase airflow. Just make sure the air can exit the room through an open vent or window.

Regularly monitor the air circulation in the greenhouse to maintain optimal humidity levels for your plants.

Try Dehumidifiers

Another effective way to control humidity is to use a dehumidifier. It can pull in humid air and condense excess moisture into a container. This appliance is especially handy in humid climates or greenhouses with high moisture levels. For larger greenhouses, make sure to look into a commercial grade greenhouse dehumidifier to ensure it has enough capacity.

Desiccants are also called dehumidifiers because they remove moisture from the air. Popular desiccants include silica gel packets and moisture-absorbing crystals. Place them in enclosed spaces in the greenhouse where moisture tends to accumulate.

Consider Alternative Methods

You can also dehumidify a greenhouse by installing shade cloth or curtains. These can minimize direct sunlight exposure and reduce humidity levels. The shade can also help regulate the temperature in the greenhouse to ensure healthy plant growth.

Proper water management can also help you control humidity in a greenhouse. Avoid overwatering plants because excess water can lead to high humidity.

Instead, water plants at appropriate intervals. Or better yet, consider using drip irrigation systems instead of overhead watering. Doing so allows you to water the roots of the plants to reduce humidity and water waste. 

What Are the Factors to Consider in Greenhouse Dehumidification?

Dehumidifying a greenhouse is not as straightforward as you might think. It is best to consider the following factors to create an optimal environment for your plants.

Greenhouse Size

One of the first factors to consider is the size of the greenhouse. It affects the power capacity and choice of dehumidification devices.

Larger greenhouses require more powerful dehumidifiers to manage moisture levels. Meanwhile, smaller ones may only need natural ventilation or small devices.

Greenhouse Construction Materials

The materials used for the greenhouse design can also affect humidity levels in your greenhouse. Consider the glazing materials, insulation, and ventilation systems available in the building. Properly seal the greenhouse to prevent excess moisture from entering. You must also ensure every vent is working to promote proper air circulation.

Climate and Outdoor Conditions

The location of the greenhouse plays a significant role in greenhouse dehumidification. The prevailing climate and temperature in your area can impact the amount of moisture entering the building.

It is best to check weather forecasts in advance. Or better yet, understand the local climate before buying dehumidification equipment. Doing so will save you money and effort in the long run. 

Humidity Requirements

Consider the needs of the plants you are cultivating in the greenhouse. Some vegetables thrive in higher humidity levels, while others prefer low humidity. That said, avoid extreme levels because they can cause different problems. Always maintain an optimal humidity range for healthy plant growth.

Water Management

Water is another important factor in greenhouse dehumidification. Avoid overwatering to prevent excessive moisture buildup. You must also install a proper drainage system to ensure water is not drowning your plants.

Energy Consumption

If you want to ensure sustainable greenhouse operation, evaluate the energy efficiency of your dehumidifiers. They can consume significant amounts of energy, which costs a lot. Consider exploring options like natural ventilation and energy-efficient models. These can promote sustainability and minimize operating costs.

Monitoring Systems

Finally, consider installing monitoring equipment to measure humidity. These include hygrometers, data loggers, and wireless sensors. You can even use environmental monitoring systems and Bluetooth-enabled hygrometer devices.

Also, check if they allow you to set an alarm or alert when humidity levels exceed the optimal amount. This feature can promote proactive humidity management.


Operating a greenhouse is not as straightforward as one might think. You must constantly regulate temperature and humidity levels to ensure your plants grow properly.

Learning about greenhouse dehumidification basics is one step toward creating a controlled environment. Set the humidity level to 50 percent or 70 percent for most plants. However, you must also consider other factors, which we covered in this article.

Do you have more questions about dehumidifying a greenhouse? Send your queries via our contact page, and we will get back to you soon!

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