How do You Increase Humidity in a Grow Tent?

Your grow tent is the home of your plants and whether the home is large or small, you need to maintain a proper environment for them. Humidity is one of the keys to keeping plants happy and growing. If you’re an indoor grower, you’ll need to learn how to control and increase humidity in a grow tent.

What is Humidity?

Humidity is the measure of water vapor concentration in the air, reflecting the moisture content of the atmosphere. Typically expressed as a percentage, it indicates the proportion of water vapor present relative to the maximum capacity the air can hold at a specific temperature and pressure.

To measure humidity in your grow tent, the easiest way is to use a digital hygrometer, which makes readings and monitoring quick and easy. If you want to keep your plants healthy and for them to live longer, you will need to control the humidity levels to a point between 45% to 75% relative humidity (RH). If your grow tent is below 40% RH, you have to take action to increase the humidity, otherwise, there will be a high risk of losing your plants.

Humidity levels below 40% RH can be dangerous for most plants because it causes plants to lose their reserve water, causing them to wilt faster, grow slower, lose nutrients, and ultimately they will die. It can also lead to poor development and lower yields in the long run.

Some plants and some grow periods require very high humidity levels, such as during the seedling or cutting periods. When you move to these stages, be sure to raise the humidity in a grow tent. The difficulty is that humidity is not easy to control, so we came up with a couple of ideas for how you can increase the humidity in the grow tent.

What is Relative Humidity?

Relative humidity (RH) is a measure of the amount of water vapor present in the air relative to the maximum amount of water vapor the air can hold at a given temperature and pressure. It is expressed as a percentage and indicates how close the air is to saturation.

Relative humidity is affected by both the actual water vapor content in the air and the air temperature. Warm air can hold more water vapor than cold air, so relative humidity values change with temperature fluctuations. For example, if the relative humidity is 50%, it means the air is holding half of the maximum amount of water vapor it can hold at that temperature.

What is Absolute Humidity?

Absolute humidity (AH) is a measure of the actual amount of water vapor present in the air, regardless of temperature. It is expressed in grams of water vapor per cubic meter of air (g/m³) or other units of mass per volume.

Unlike relative humidity, absolute humidity does not change with temperature variations. It represents the total moisture content in the air and is often used in meteorology and engineering applications. Absolute humidity provides a more direct measurement of the moisture content in the air but does not provide information about the air’s saturation level.

Ways of Increasing Humidity in a Grow Tent

1. Adding a bucket of water

Since humidity is water vapor, you can add a bucket of water or several small bowls of water into your grow tent. As the water evaporates you will raise the humidity level in the tent. Be sure to refill the water when necessary.

2. Watering the plant by using a sprayer

Using a spray,  mist the air inside the grow tent multiple times. As the water droplets evaporate, they will raise the humidity level inside the tent. In order to keep the humidity at a constant level, mist the leaves and roots of your plants every day. Check the RH every morning. If the humidity level falls too much, be sure to mist the plants again.

3. Hanging wet towels

Just as in the other methods, hanging a big wet towel or several small wet towels in your grow tent will make water evaporate in the air. This is an easy way of increasing the humidity level. Remember, make sure the towels are not too close to your grow light or other heat sources, since the towels could be burned.

4. Removing the grow lights

Grow lights can create a lot of heat so removing them will decrease the ambient heat level within the grow tent. Less heat will help the air retain humidity. As an aside, it is important to find a proper balance between heat and humidity.

5. Lowering your fan’s speed

Air circulation reduces the ambient humidity in your grow tent by pulling or pushing the moisture trapped in the air. By keeping your fan at a medium or low speed you will be able to stabilize humidity levels while keeping fresh air circulating in the tent. Alternatively, you can also shut off the ventilation system temporarily—for an hour or two—to help the humidity level stabilize.

6. Reducing the air conditioner’s temperature

Decreasing the temperature in the room can raise humidity as well. Using an air conditioner is an easy way to increase the humidity without adding any extra water. However, some plants do not prefer cool environments, so be careful with your plants. It is always a good idea to have a thermometer in the tent with your plants so you can keep an eye on the temperature, regardless of the humidity.

7. Using a humidifier

The most obvious way to increase the humidity in a grow tent is to use a humidifier. A humidifier is a small device that is easy to use, just fill the water tank and turn on the device and over time it will fill the air with water vapor.

8. Adding more plants

Plants respirate similarly to animals, and part of what they “exhale” is water vapor. This transpiration results in raising the humidity in a grow tent. Adding more plants to a grow tent will increase transpiration and bring humidity levels up. You can add plants other than your main crop, too! It’s an excellent opportunity to try something new.

Wrap-up

Every plant has its preferred humidity levels—whether you’re growing orchids or succulents, you will need to mimic the perfect growing environment for your crop. Yet, humidity levels vary through stages of growth, so you will need to carefully measure and adjust humidity through the growing cycle to accommodate your plants’ changing needs.

Luckily, there are some quick and easy ways to make these adjustments—just make sure you know the needs of your specific plant or specific strain before you grow so you can plan accordingly. Happy growing everybody!

If you have any questions, please don’t hesitate to reach out to us!

And be sure to check out our other blog posts for useful tips on becoming a great grower!

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