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How To Raise Humidity In a Grow Tent

Table of Contents

Defining Relative Humidity And Why It Matters To Your Plants

How Does Low Humidity Affect Plants?

Affordable Tips For Increasing RH

  • Decrease The Speed Of Your Fans
  • Lower Your AC Temperature
  • Take Out Half Of Your Fluorescent Lights
  • Add Water Sources To The Tent
  • Products That Will Help Raise RH

  • Get A Humidifier
  • Use Propagation Set-Ups
  • Buy An AC unit 
  •  Final Thought




    Did you know plants lose a significant amount of water through the tiny holes on their leaves called the stomata? Only 5% of water absorbed is retained for building new plant cells, and this is why water is constantly needed to keep plants from becoming dehydrated. Apart from watering the plant, humidity (the quantity of water held in the air) is very important to the health of your plants. It's important to monitor the relative humidity (RH) level in your grow tent. But why is it important? Let's look into the importance of relative humidity and how to raise the humidity in your grow tent.

    Defining Relative Humidity And Why It Matters To Your Plants

    As an indoor grower, it's important to know that different plants have different humidity requirements. Seedlings need 70-80% RH, 50-60% RH when sprouting begins, 40-50% RH during the flowering phase, and 45-50% when harvesting.

    Temperature and humidity levels are crucial to providing a How Does Low Humidity Affect Plants? The humidity levels fluctuate based on temperature; the higher the temperature, the higher the relative humidity level. And as you might have guessed, the lower the temperature, the lower the relative humidity level.

    Humidity ranges of about 45-75% are optimal for plant development. If your grow tent has a humidity level of 20-40%, then you'll need to act fast to save your plants. 

    How Does Low Humidity Affect Plants?

    During low humidity levels, a high vapor pressure deficit exists between the leaves of the plants and the air, and since plants still have the need to breathe through their leaves they are exposed to dry environments.

    Plant dehydration will cause the stomata to close, preventing the plant from absorbing further water through the leaves. To counteract this drying effect, your plants will attempt to get more water through the roots, but this is impedes their growth.

    Low relative humidity forces the roots to draw on so much water, which could contains extra nutrients, that it can cause nutrient burn (also known as nutrient lockout).

    Lack of humidity may also trigger plant desiccation, which exposes the plant to infestations by molds, white powdery mildew, and spider mites.

    Affordable Tips For Increasing RH 

    Thanks to research and innovation, you can regulate the humidity of your grow tent to ensure your plants get the right humidity levels. Below are some strategies you can implement to increase the humidity of your indoor garden.

    Decrease The Speed Of Your Fans

    Ventilation can cause humidity levels decrease in two ways. First, the movement of air within the tent dries out moisture. Second, moisture is carried out by the air that is vented out of the tent by the extraction fan. Obviously, there are times when reducing the amount of air you vent out of the tent is impossible with this method, especially you have fewer fans, or you're having problems with the temperature, and you need your fans running at full speed.

    However, if you can reduce the extraction fan's power without creating other problems, this is a simple way to raise the relative humidity. Many fans have a selection of speeds. The important thing is to make sure you have enough fan capacity for the scale of your tent.

    Lower Your AC Temperature

    Lowering the AC temperature in your grow tent will increase the relative humidity. When compared to warm air, cold air needs less moisture to become saturated; meaning, the colder the tent, the higher humidity.

    Obviously, you don't want to go below the optimal temperature required for your plants. Put it as low as it can go based on your plant species. 

    Take Out Half Of Your Fluorescent Lights

    Of all the grow lights, fluorescent generates the most heat. So, as you might imagine, having too many of them in your grow tent can lower your humidity. To lower the temperature and raise humidity, without losing your source of light, you need to do the following:

    • First, switch off the lights and wait for them to cool down for around 5 minutes.
    • Then remove some of the excess bulbs from their sockets leaving only a few depending on the size of your grow tent.
    • Place your bulbs in a safe place in case you'll need them in the future. 
    • Before you know it, the temperatures will be lowered, and the humidity level will increase.

    Add Water Sources To The Tent

    You can dip some towels in water and hang them around the air vents to evaporate the moisture as the air flows in. The moisture escaping the towels will increase the humidity in the room. You can also place bowls or buckets of water around the airflow systems to humidify the tent. Although this is not a very reliable method, it's still worth a shot to raise the humidity levels.

    Products That Will Help Raise RH

    In addition to the affordable methods, there are products you can invest in to increase humidity. In a nutshell, a humidifier, a propagator, and a and efficient AC unit will keep you in control of humidity levels in your tent.

    Get A Humidifier 

    Owning a humidifier can be the best decision you've ever made. With this device, you can easily increase the humidity level of your grow tent. When you want to purchase a humidifier, there are several things you should consider. First, ensure it has a humidistat will allow you to program it to switch off when your preferred humidity is reached and turn back on when it falls below that level. Also, it's prudent to buy a humidifier that has ample moisture capacity, so you won't have to refill it repeatedly. 

    Use Propagation Set-Ups

    Seedlings can germinate on their own, so by utilizing propagators to raise the humidity in your grow tent, you can increase the success rate of developing plants. Propagators are small incubators used to grow seedlings in the best possible conditions. They usually consist of a translucent cover and an undertray filled with a growing medium such as soil. 

    A propagator will maintain high humidity levels in your grow tent, ensuring that your seedlings' root systems are not stressed while they develop and grow. The cool part is that you can even build your own propagator using the plastic packaging lying around your home. Or order from our affordable selection of propagation set-ups.

    Buy An AC unit

    Buying an AC unit may seem to be expensive, but the benefits are worth the investment. An AC unit is the best equipment to regulate the temperature. Keep in mind that since cold air has a higher density than hot air, it falls to the bottom. A lower temperature indicates that the air is moist and has a substantial volume of water vapor. Under ideal conditions, a standard, well-ventilated grow room should be held between 75 and 85 degrees Fahrenheit. However, the temperature may be adjusted to meet the needs of your plants.

    Final Thought

    Generally, low temperatures produces a humid atmosphere, while higher temperatures result in less moisture in the air. With these tips, you can now confidently grow plants in a grow tent without worry. The point here is to know your numbers, temperature, light, and humidity requirements for your specific plants. This knowledge, coupled with the implementation of the strategies we have discussed, will bring you bigger yields!


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