Bill Teller


How To Control Humidity In Grow Tent? Plants need to be grown at a suitable temperature in a grow room. The temperature, humidity, light, and proper care per each plant’s need can make your grow room green and clean.

Not only all these considerations improve the growth, but they also protect them from all kinds of fungi and diseases. So growing plants in a grow room is not only fun. It is an activity that, if done correctly, can


bring you a lot of plants and peace. And for that, you will need to know the temperature and level of humidity required for yielding healthy plants and all other factors affecting their growth.

Not too low and not too high, there is an ideal level of humidity discussed in this article, along with how to lower high humidity in a grow room.

Ideal Humidity For Plants

Like temperature and other factors, a specific humidity level is also significant for keeping plants well hydrated. Humidity in the atmosphere depends on temperature and is always measured by relating it to the temperature.

So the relative humidity required for plants’ growth is almost 50 to 70%, with more specifications for some plants. If we talk about cacti, they don’t need that much water to survive easily, even in low humidity levels.

Similarly, some plants need a relatively higher percentage of humidity.
The beneficial percentage of humidity needed by flowering and vegging plants is:

  • 40% to 50% for Flowering plants
  • 50% to 70% for Vegging plants

Dangerous Humidity for Plants

On the other hand, if the humidity level in the grow tent increases and gets more than 70 %, it can threaten the plants. In high-level humidity, plants grow slower and are more easily attacked by fungus, mildew, and mold.

If the humidity level rises more than 70%, the buds and roots of flowering and vegging plants start to rot due to the moisture. So make sure to keep the humidity level low enough that it is sufficient for the growth of plants.

Devices to Measure Humidity

You can use some measuring devices for measuring the temperature or humidity in your grow room. It is better to keep these measuring devices at a distance from the AC and humidifier/dehumidifier so that they don’t sense the temperature of only cool or warm areas of the grow room.

Only by finding out the humidity level of your grow tent can you make it higher or lower humid for the plants. Also, it depends on the kind of plants you want to grow in your grow room. For measuring the humidity level, you can use the following measuring devices.

  • Thermometer

Use a thermometer to get the accurate temperature of the grow room. Most indoor growers use a digital thermometer as it gives the more clear result, and it also makes it easier to keep a record of the results.

Keeping an estimate of temperature is as necessary as humidity because the temperature of the grow room affects the process of photosynthesis in plants.

The temperature of grows room should be average, not too high or low as in both cases it is bad for the plants. Also, the temperature increases or decreases the grow room’s humidity level.

  • Hygrometer

Another helpful device for measuring humidity in the grow room is a hygrometer. It is different from the hydrometer used to measure the density of a liquid, while a hygrometer measures the humidity in the atmosphere. Therefore, don’t get confused between the two for buying a device for your grow room.

  • Moisture meter

Besides a thermometer and hygrometer, keep a moisture meter to check the soil’s moisture level. It will help you protect the plant’s roots from rotting, and the roots will grow out into a healthy plant. Also, it enables you to schedule the watering of your plants according to their need.

How to Maintain Humidity Level in Grow Room

There are some techniques to maintain or lower the humidity in a grow room. Expert indoor growers or gardeners follow some or more ways to reduce the humidity level and check it repeatedly to keep it maintained.

These techniques are simple to understand. Read the following points that can help you lower the humidity in the grow room.

1-Install Air Conditioners

The only way to keep the temperature of the tent lower in summer is to install air conditioners in it. Depending on the size of grow room, choose the right one that is reliable for maintaining the temperature at the optimum level.

air-condition-How To Control Humidity In Grow Tent

If the AC units are large, they will make the grow room too cold too soon and affect the growth of plants. On the other side, an AC with low units will slowly decrease the temperature and make the atmosphere better for plants.

2-Dehumidifiers for Decreasing Humidity

An excellent indoor gardener should have both a humidifier and dehumidifier that he can rely on whenever needed. A dehumidifier is used to draw out moisture from the air. As soon as the moisture from the air decreases, the humidity level also decreases.

But a dehumidifier can only do its job correctly if suitable for your grow room environment. Choose a dehumidifier with more capacity to store water for a large grow room.

Also, If your grow room is located in a place with moist air, check the power of a dehumidifier and the type of plants you grow. It should be able to remove the same volume of water that the plants in your grow room transpire.

Also, an automatic dehumidifier with sufficient water storage capacity is always a good option.

3-Do Remedies for Unabsorbed Water

Always try to water your plants as much as they need because the extra water remains in or on the soil. This unabsorbed water then increases the humidity in the grow room. Therefore, it’s necessary to remove the excess water.

Besides, there are water-absorbent soils available in the market. Applying these soils can also decrease humidity in the grow room.

4-Proper Ventilation System

The more air moves in and out, the more it decreases the humidity level in the air. You can create big or small holes (according to the size of grow room for proper ventilation.

This will considerably lower humidity in the grow room with increased air circulation as the humid air will vent out, and fresh air will get inside.

5-Insulating Your Plants and Grow Room

Proper insulation is done to protect plants in highly humid areas. Moisture will protect the plant from fungus and other plant diseases.

Also, to fully insulate your grow room, there are several methods from which closed cell spray foam is the best for growing healthy plants.

6-Maintain Appropriate Temperature

The temperature inside the growing room should be appropriate for maintaining a relative humidity level lower than 70% for the healthy growth of plants.

Keep rechecking the temperature to keep it ideal for humidity and take measures to maintain it.

How To Control Humidity In Grow Tent | Grow Room |

Water vapors evaporate at higher temperatures, decreasing the humidity in the air. In simple words, the one decreases as the other increases. Therefore keep the temperature high but not too high to make the grow room too hot.

Conclusion – How to Lower Humidity in Grow Room

A grow room should be at the best temperature, humidity level, and space for the best growth of plants. Keep learning new methods to maintain a healthy environment by lowering the humidity level and considering the specific percentage of humidity for various plants.

Also, you can use the methods mentioned above in conjunction or only one, depending on your need.

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