How to Adjust Humidity Levels in a Greenhouse

Maintaining the proper humidity levels in your greenhouse is crucial for the health and growth of your plants. Here are some tips on how to adjust humidity levels in a greenhouse.

5 Tips to help you Adjust Humidity Levels in a Greenhouse

Depending on where you live, some of these tips will be more helpful than others. In some areas, for instance, you’ll want more humidity, in other areas less. You’ll also want to learn more about the specific plants in your greenhouse and what humidity levels they prefer.

Tip 1: Ventilation

Good ventilation is key to regulating humidity levels in a greenhouse. Make sure to have vents or fans installed to allow for proper air circulation. This will help prevent excess moisture from building up and keep humidity levels at an appropriate level.

Tip 2: Appropriate Watering

Another way to control humidity levels is by managing watering. Overwatering can lead to excess moisture in the air, raising humidity levels too high. Conversely, under-watering can result in too little humidity, which can harm your plants. Be sure to water your plants properly, based on their needs and the conditions in your greenhouse.

Tip 3: Use a Dehumidifier

If increasing ventilation is not enough to lower humidity levels, consider using a dehumidifier. A dehumidifier works by removing moisture from the air, which helps to reduce humidity levels. There are various types of dehumidifiers available in the market, so make sure to choose one that is suitable for the size of your greenhouse.

Tip 4: Shade

Shade can be an excellent way to control your greenhouse temperature and humidity levels.

Using a shade cloth can help regulate temperature and humidity levels in a greenhouse. It can help reduce the amount of direct sunlight that enters the greenhouse, which can cause excess heat and humidity.

A shade cloth with a density of 30% to 50% is generally recommended for most plants. This will allow enough light to reach the plants while also providing sufficient shade to keep the temperature down.

Tip 5: Desiccants

Desiccants are materials that can absorb moisture from the air. Silica gel is probably the most common desiccant found in the industrial world. It’s what is in the tiny packets found in packaged food products to help prevent rot. You can use it in your greenhouse as well.

If you prefer a more natural route, here are some organic desiccants you can put in your greenhouse:

• Activated charcoal or carbon made from coconut shells or other plant materials
• Calcium chloride made from limestone and brine
• Montmorillonite clay, also known as bentonite, which is a naturally occurring absorbent clay

Place the desiccants in a small container and spread them out in different areas of the greenhouse.

The Importance of Humidity for Greenhouse Plants

Greenhouse plants require a certain level of humidity to thrive. If the humidity levels are too low, plants can become dehydrated and wilt. Conversely, if the humidity is too high, it can cause excess moisture to build up on plant surfaces, leading to the growth of mold and mildew.

Maintaining proper humidity levels and knowing how to adjust humidity levels in a greenhouse is key to ensuring the health and growth of your plants.

Key Humidity Terms

Here are a few concepts to keep in mind to help you adjust the humidity levels in your greenhouse appropriately.

Relative Humidity

Relative humidity refers to the amount of moisture present in the air compared to the maximum amount the air can hold at that temperature. This is expressed as a percentage, with 100% being the saturation point where the air cannot hold any more moisture. Adjusting your humidity levels appropriately can make or break your greenhouse. Too much humidity can lead to mold, mildew, and disease, while too little humidity can cause plants to dry out and wilt.

Dew point

Dew point is the temperature at which moisture in the air begins to condense into liquid water. When the temperature drops to the dew point, water droplets form on surfaces and can cause damage to plants and equipment. It is important to monitor the dew point in a greenhouse to avoid potential problems.

To do this, you can use a hygrometer that also measures dew point, or a separate dew point meter. These devices measure the relative humidity and temperature in the greenhouse and calculate the dew point based on these measurements.

When using a hygrometer, make sure to place it in an area that is representative of the overall conditions in the greenhouse. For example, avoid placing it directly in front of a ventilation fan or near a heater, as these can affect the readings. It’s also important to calibrate your hygrometer regularly to ensure accuracy.

If you prefer to use a separate dew point meter, you can place it in a location that is easily accessible for monitoring. Keep in mind that some meters may require periodic maintenance, such as replacing the desiccant material or recalibrating the device.

Vapor Pressure Deficit (VPD)

Vapor Pressure Deficit is a measure of the difference between the amount of moisture in the air and the maximum amount of moisture the air can hold. It is an important factor to consider when managing humidity in a greenhouse. A high VPD means the air is dry and can cause plants to transpire too much, while a low VPD means the air is too humid and can cause mold and disease.

What is Transpiration?

In short, it’s plant sweat.

When a plant transpires, it means that it is losing water vapor through small pores, called stomata, on the surface of its leaves. This process is similar to sweating in animals and is essential for the plant’s survival, as it helps to regulate the plant’s internal temperature and maintain water balance.

Transpiration also plays a critical role in nutrient uptake and photosynthesis, as water is needed to carry nutrients from the soil into the plant’s roots and to help convert light energy into chemical energy. Overall, transpiration is a crucial process that helps to ensure the health and growth of plants.

A Heat Exchanger

A heat exchanger is a device that transfers heat from one fluid to another. In a greenhouse, a heat exchanger can be used to control humidity by regulating the temperature of the air. By passing hot, humid air through the heat exchanger, the moisture can be condensed and removed from the air, resulting in lower humidity levels. The cooled, dry air can then be reheated and recirculated back into the greenhouse.

This is a highly effective way to maintain proper humidity levels in a greenhouse while also controlling temperature.

What Level of Humidity is Appropriate in a Greenhouse?

The appropriate level of humidity in a greenhouse depends on the specific plants being grown. In general, most plants prefer a humidity level between 50-70%. However, some plants may require higher or lower humidity levels, so it’s important to research the specific needs of your plants.

How Do I Know If My Greenhouse Humidity Level is Off?

You can use a hygrometer to measure the humidity levels in your greenhouse. A hygrometer is a device that measures the amount of moisture in the air. It can help you determine if the humidity levels are too high or too low, allowing you to make the necessary adjustments.

Humidity Levels and the Effect on Plants

When the humidity is too high, it can cause excess moisture to accumulate on the plant’s leaves, leading to fungal diseases and rot. Additionally, high humidity can reduce the plant’s ability to transpire, which can lead to a buildup of excess moisture in the soil, leading to root rot.

On the other hand, when humidity levels are too low, plants can become dehydrated and wilt. This can also cause damage to the plant’s leaves and stems, making them more susceptible to pests and diseases. Low humidity can also increase the rate of transpiration, which can cause the plant to lose more water than it can absorb, leading to dehydration and ultimately, death.

A Useful Video on How to adjust Humidity Levels in a Greenhouse

Can You Automate Humidity?

Yes, you can automate humidity in a greenhouse by using a humidistat. A humidistat is a device that measures the humidity levels and turns on a humidifier or dehumidifier to maintain the desired level. This can be a useful tool for maintaining consistent humidity levels in your greenhouse, especially if you are unable to monitor and adjust levels manually.

Conclusion

Hopefully you have a better understanding of how to adjust the humidity levels in your greenhouse. It may seem like a lot, but get out there and try some of these things and we’re sure you’ll find the appropriate humidity levels for your plants.

By following these tips and techniques, you can maintain a healthy and productive greenhouse environment for your greenhouse garden. With the right amount of humidity, your plants will flourish and provide you with beautiful and bountiful harvests.