Fogging System For Greenhouses: How Evaporative Fog Cooling Impacts The Health Of Your Crops

As temperatures rise and global weather patterns become increasingly unpredictable, the world of agriculture is seeking effective, energy-efficient solutions to keep crops healthy. That’s why the utilization of fogging systems is extremely popular among cultivators. An innovative technique that harnesses the power of evaporative cooling, a fogging or misting system can drastically transform the health and yield of your crops.

Fogging systems operate by creating a fine mist or \’fog\’ in the greenhouse, which reduces temperatures and increases humidity levels in a controlled manner. The fog particles, usually about 6 to 10 microns in size, evaporate quickly and cool the surrounding air.

One of the reasons why fog-based greenhouse misting systems are so highly recommended is because of the incredible degree of control they offer over temperature and indoor humidity. Humidity control is critical for the well-being of crops. Just as humans need the right balance of temperature and humidity for comfort, plants also thrive best under specific environmental conditions.

When humidity levels become excessively low, the plant\’s stomata respond by closing in an effort to conserve water, impeding the process of transpiration. Consequently, the plant becomes reliant on its roots to absorb water, which can elevate nutrient uptake to potentially harmful levels. This excessive absorption has the potential to cause irreversible damage to the plant. Conversely, an excessive amount of moisture creates an environment conducive to the growth of molds and diseases, posing an equally significant risk.

Effectively maintaining this delicate balance is of utmost importance, and fogging systems demonstrate as an invaluable utility to the commercial greenhouse industry.

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Understanding Fogging Systems for Greenhouses

A fogging system is primarily made up of a high-pressure pump, a distribution network of pipes or tubes, and a series of nozzles. The high-pressure pump is the heart of the system; it forces water through the distribution network in a controlled manner. As the water reaches the nozzles, it is atomized into microdroplets, and a fine mist or \’fog\’ is created.

These droplets are incredibly small, ranging from 6 to 10 microns in diameter, and they evaporate rapidly when they come into contact with the air, reducing the ambient temperature through a process called evaporative cooling.

This brings us to some of the key benefits of using a greenhouse cooling system:

Precision Humidity and Temperature Control

If you want to control the temperature for the specific needs of your individual crops, a fogging system has got you covered. For instance, strawberries thrive in extremely specific temperatures and humidity levels; by adjusting the fogging system to maintain these specific conditions, growers can achieve higher fruit quality and yields.

Effective Cooling

In a greenhouse growing heat-sensitive crops like lettuce, high temperatures can result in plant heat stress and reduced crop quality. Fogging systems lower the temperature by evaporating tiny water droplets, potentially reducing the ambient temperature by up to 15°F. This kind of control gives growers the potential to drop temperatures within the greenhouse during the hottest part of the day, effectively reducing ambient temperatures immediately.

Energy Efficiency

Consider a 100,000-square-foot commercial greenhouse. A conventional cooling system might lack precision and conservation of natural resources. But with a modern fogging system, equipped with a variable-frequency drive (VFD), energy consumption is designed to be minimal.

A VFD controls the speed of the motor that drives the pump, allowing it to adjust its energy usage to use only what power is required at the time of application. This not only saves energy but also increases the longevity of the motor due to less wear and tear. Over the course of the system\’s lifetime, this can result in substantial cost savings.


MicroCool’s fogging systems are customized to suit all crop types and greenhouse sizes. For instance, in a large-scale greenhouse that grows crops such as cucumbers or tomatoes, a fogging system could be designed to accommodate different zones with varying humidity levels and temperatures depending on the ventilation, sun exposure, and other factors that affect the microclimate. This allows the grower to optimize the cooling or humidification for each zone to prevent issues such as heat stress or fungal diseases.

This versatility shows how adaptable this fine-misting technology is when it comes to managing diverse crop requirements within the same structure.

In large-scale commercial greenhouses, having such a reliable system to manage temperature and humidity is a no-brainer. If you are growing crops like lettuce, spinach, and radishes – which require relatively high humidity and cooler temperatures – a fogging system could assist in maintaining these conditions with utmost accuracy, even on the hottest of days. This ensures optimal growth and prevents issues like tip burn so you get better yields and crop quality.

Impact of Humidity on Plant Health

For plants, humidity is as important as sunlight, temperature, and nutrient supply. Each plant variety has a particular humidity range in which it flourishes, and maintaining this perfect range is crucial for the health and productivity of crops in a greenhouse.

Effects of Low Humidity

Low humidity levels experienced in arid regions or during the winter season can have a damaging impact on plant growth and development. When the greenhouse air becomes too dry, plants can experience transpirational stress. Transpiration, the process where water is lost from the plant through its leaves, increases in low humidity conditions. This can lead to symptoms such as wilting, stunted growth, and in severe cases, plant death.

In a greenhouse growing tomato plants, an accurate relative humidity level is essential. If the humidity drops below the required levels, the plant will lose water through its leaves and rely on absorption from the roots, causing the plant to exhibit wilting, premature leaf drop, and decreased fruit production.

Effects of High Humidity

On the other end of the spectrum, excessively high humidity can be just as harmful. When humidity levels are too high, it reduces the rate of transpiration, slowing the plant\’s uptake of water and nutrients. This can lead to weaker, slower-growing plants – but that’s not all. High humidity can create an ideal environment for fungal diseases and pests.

Roses, for one, grown in commercial greenhouses are often susceptible to a fungal disease called Botrytis cinerea when relative humidity levels exceed 85%. This disease, also known as gray mold, thrives in high humidity and can quickly devastate a crop if left unchecked.

Evaporative Fog Cooling: How It Works

The misting systems mentioned earlier operate on a remarkably simple yet effective principle – the conversion of liquid water to water vapor. When water is atomized into very tiny droplets through high-pressure nozzles, the resulting fog quickly flash evaporates into the air. This causes the surrounding temperature to decrease as the water evaporates.

In a greenhouse, this can have profound effects on crop health. Just as we feel refreshed on a hot day when we step into an air-conditioned room, plants respond positively to a cooler, more humid environment. This cooling effect can:

  • Protect sensitive crops from the damaging effects of overheating
  • Promote proper cellular functions
  • And ultimately support robust plant growth and high-quality yields

You can see a good example of this in MicroCool\’s systems, which are expertly designed to deliver precise cooling and humidity control. Our IBEX pump units, as utilized by Origin Organics, maintain constant relative humidity and cooling levels. These systems are not only effective in hot climates but can also adapt to locations with more variable weather conditions.

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Advantages of Fogging Systems for Greenhouse Humidity Control

If you’re looking for truly automated, state-of-the-art technology to manage your greenhouse environment, installing an industrial-grade greenhouse humidification system like MicroCool can offer an impressive range of benefits.

Improved Plant Transpiration

The controlled environment you have with a commercial greenhouse fogging system significantly increases plant transpiration and nutrient uptake. MicroCool\’s advanced units create a super fine mist which increases relative humidity, and as a result, helps maintain optimal stomatal activity for efficient nutrient absorption.

Prevention of Plant Stress and Wilting

A high-pressure fog system can regulate the interior climate conditions effectively. During extremely hot summer days, for instance, the evaporative cooling effect of the fog lowers the greenhouse temperature to prevent plant stress and wilting which can lead to loss of yield.

Reduction in Fungal Diseases and Pests

By maintaining optimal humidity levels, fogging systems make the environment less favorable for pests and fungal diseases. Origin Organics, a greenhouse facility in Canada, found that after installing a MicroCool fogging system, they saw a 50% reduction in pest issues. Their crops were healthier and better equipped to deal with potential threats like red spider mites and aphids.

Energy Efficiency and Cost-effectiveness

The MicroCool fogging system features cutting-edge technology like variable frequency drives that allow it to operate at peak levels while consuming less energy. It\’s estimated that high-pressure fogging systems can be up to 30% more energy-efficient compared to traditional cooling systems, which translates to considerable cost savings for large-scale commercial operations.

Consistent Crop Quality

Keeping your crop vital is key to ensuring its quality – a high-pressure fogging system can help with this as well. Many growers have found that using a fogging system results in consistent fruit quality throughout the growing season. Rather than having to close thermal screens and block light, you can use the fog to reduce stress and keep your plants healthier, improving the quality of the harvest.


One often overlooked benefit of fogging systems is their adaptability. Whether it\’s a vegetable crop, like tomatoes and cucumbers, or more exotic plants, these systems can be adjusted to fit the precise needs of healthy plants.

Types of Fogging Systems for Greenhouses

When it comes to greenhouse humidity control, what kind of fogging system you choose is a major factor to consider. Each system works differently and has its own set of pros and cons.

High-Pressure Fogging Systems

These systems force water through nozzles under high pressure, typically between 500 and 1500 PSI. The result is a fine mist or fog of tiny water droplets that can evaporate quickly, and cool the surrounding air plus increase humidity.

MicroCool offers some of the most advanced high-pressure misting systems, which deliver optimal cooling and humidity control for a wide variety of crops. These are particularly effective in larger commercial greenhouses because they can cover a wide area and can be customized to specific climate conditions.

Low-Pressure Mist Systems

Low-pressure systems operate similarly to high-pressure systems but at a lower pressure range, usually around 50 to 70 PSI. Because of the lower pressure, the droplets produced by these systems are larger and may not offer adequate evaporation to either raise humidity levels or rapidly reduce temperatures inside the greenhouse. This means they can potentially wet the plants and the ground, which may not be ideal in some situations. Low-pressure systems are usually cheaper to install and operate but may not be as effective or versatile as high-pressure systems.

Ultrasonic Fogging Systems

An ultrasonic fogging unit uses ultrasonic waves to atomize water into a very fine mist. It’s generally used in smaller, enclosed spaces because it can\’t distribute the mist over a large area as effectively as a high-pressure system. It’s also less effective in open or ventilated greenhouses because the fine mist can easily be carried away by air currents.

With that said, ultrasonic foggers can be a good choice for certain specialized applications, such as propagation areas, where high humidity is required.

In comparison, high-pressure fogging systems like MicroCool offer more precise control over the greenhouse environment. They are typically more energy-efficient and effective at cooling and humidifying a large area without wetting the plants or the ground.

On the other hand, low-pressure and ultrasonic systems might be a good choice for smaller greenhouses or specific applications, but they generally don\’t offer the same level of control or effectiveness. Ultimately, the choice between these systems will depend on the specific needs and constraints of your greenhouse.

Choosing the Right Fogging System for Your Greenhouse

If you’re considering investing in a fogging system, you need to think strategically so you can achieve the best climate control for your crops. Here are some key elements to consider:

Crop Requirements

Each crop type has its unique climatic preferences. Different crops may require different levels of humidity and temperature to grow well and produce high-quality yields. Also, some crops might need higher or lower humidity levels during certain growth stages. For example, most crops benefit from high humidity levels during the propagation stage to ensure a healthy start. Pertaining to this, as these plants mature, the humidity levels may need to be adjusted to reduce the risk of stress and diseases.

So, when picking a fogging system, select one that is capable of creating the specific conditions your crops need for each of their growing stages. This means choosing a system that not only cools the environment but also has the ability to precisely regulate humidity levels as per your crop’s needs.

Climate Conditions

Your local climate also plays an important role in determining the right system. The external weather conditions can directly impact the internal conditions of your greenhouse, and your fogging system should be able to compensate accordingly.

For a greenhouse situated in a region characterized by dry, hot conditions, like Arizona, where the air is usually low in humidity, the temperatures can often soar above comfortable levels for most crops. So a cooling system with strong capabilities is necessary to bring down temperatures inside the greenhouse.

To give you a better idea: if your greenhouse is in a place with high summer temperatures reaching up to or above 100°F, a high-pressure system can potentially lower the temperature by about 15-20°F. That\’s enough to create a comfortable environment for your crops to flourish, even under scorching outside temperatures. So, if you\’re dealing with a hot, arid climate, a MicroCool fogging system would be an excellent choice due to its superior cooling and humidifying capabilities.

On the other hand, if your greenhouse is located somewhere with a more temperate climate, where extreme heat is not a significant concern, you might not need such intense cooling power and a smaller system could be utilized to manage temperature in the summer and humidity in the winter when heaters are on. A high-pressure system that can be customized to your needs is important.

Size of Your Greenhouse

The total area of your greenhouse directly impacts the capacity of the fogging system needed. Larger greenhouses may require more powerful or multiple fogging units to achieve the desired humidity or temperature.

A commercial greenhouse that spans several acres would need a robust, high-capacity fogging system to ensure every plant receives the right amount of moisture and cooling. On the other hand, smaller greenhouses could function optimally with a less powerful system.

Layout and Design

The way your commercial greenhouse is designed will also be considered when calculating a fogging system for performance and efficiency, as well as the uniformity of the cooling and humidification. So make sure to consider the following factors:

Ventilation: Good ventilation – removing hot air and bringing in fresh air – ensures continuous flash evaporation can effectively take place to cool the air inside the greenhouse. It helps to regulate the temperature, prevent heat buildup, and maintain a healthy atmosphere for your plants. So, when selecting a cooling system, you will want to make sure it works well with your greenhouse\’s ventilation setup.

Air flow: It\’s important to have proper air circulation so that the cool air reaches all parts of the greenhouse. This helps to avoid any \”hot spots\’\’ and ensures that all your plants receive the cooling benefits. An effective cooling system should work in harmony with the airflow in your greenhouse, distributing the cool air evenly.

Number of bays: Each bay in your greenhouse functions as an individual unit within the larger greenhouse space. This means each bay may have a different temperature and humidity profile, based on factors like sunlight exposure, plant types, and ventilation rate.

If you have multiple bays, you may need to install separate cooling units or zones for targeted cooling for each bay. This will allow you to customize the cooling based on the specific needs of the plants in each bay.

Type of greenhouse: Another important factor is the construction material of your greenhouse; most are made of glass, polycarbonate, or polyethylene. Each material has different properties that impact how heat and sunlight penetrate the greenhouse. Glass, for instance, may allow more sunlight in but can also trap heat, while polycarbonate or polyethylene materials may provide better insulation but with different light transmission qualities.

Some greenhouses may have a larger surface area or height, which can impact the heat retention and air circulation within the structure. If your greenhouse has additional features like thermal screens, shading systems, or energy-saving technologies, it can also affect your cooling requirements.

Maintenance and Upkeep

Nobody wants to buy a piece of equipment that will take a lot of time and resources to maintain. The components of your fogging system should be accessible and simple to clean or replace when necessary. For example, the nozzles can get clogged over time due to mineral deposits from water, so a system with adequate water filtration and purification is beneficial and makes for easy-to-clean nozzles.

A unit that\’s built with high-quality, durable components will require less frequent maintenance and is less likely to break down, resulting in fewer disruptions to your crop\’s growth cycle. Look for systems that use materials resistant to corrosion and wear, like stainless steel, so the system stays in good condition despite the damp environment of the greenhouse.

Also consider the level of after-sales support and warranty offered by the fogging system manufacturer. Companies with a strong commitment to customer service can guide you through the maintenance process, provide troubleshooting assistance, and help resolve any issues quickly.

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Give Your Plants the Best with MicroCool\’s Advanced Fogging Systems

Whether you are a family-owned organic greenhouse or a large-scale commercial operation, MicroCool\’s cutting-edge technology and commitment to quality can help you achieve all your greenhouse growing goals. Our fogging systems offer:

  • Superior humidity control for optimal growth conditions
  • Advanced cooling capabilities to minimize plant stress
  • Efficient energy use to reduce consumption and related costs
  • Durable and quality components that are easy to maintain
  • Flexible equipment options for all types crops and greenhouse sizes
  • Enhanced plant health to reduce pest issues and boost overall crop vitality

With MicroCool, you are not just investing in a fogging system, you are investing in the growth and health of your plants. To learn more about our evaporative fogging systems, please call us at 760-322-1111. You can also get in touch with us online or drop an email at