How to Raise Humidity in Grow Tent

There are several things you have to keep in mind whenever you consider raising plants of different kinds. This is most especially true when you plan to do so inside a Grow Tent.

This medium allows you to take care of different plants year round, and grow certain produce regardless of the current weather.

They are more controlled and usually make use of hydroponics rather than conventional soil.

Some of the benefits  of using the grow tent are the more efficient absorption of nutrients for the plants and  keeping the potentially harmful elements found in soil, such as parasites, extra dirt, mold, mildew, and eggs and/or larvae of plant-eating insects at bay.

Apart from the basics, such as regular cleanup of the system, quality of the seeds and seedlings, and fertilizers, other important factor worth keeping in mind, in order to keep young plants alive and healthy would most definitely be the humidity of the surroundings, or simply put, the amount of water vapor in the air.

This article would aim to explain how and why humidity plays this particular role in the growth of plants, as well as ways on how to increase its levels, should the levels be found out to be low.

Importance of High Humidity

One of the reasons why humidity is something that should be kept at a relatively high level is due to the fact that plants need water to live. While they could get it from the roots, the reality is that plants also get this water from other parts as well.

In a more specific sense, they also absorb water from their stomata through the water vapor in the air. If there is little to no humidity where they are planted, this would rob them of the opportunity to get water for their growth and development.

Baby plants are in their most critical phase, and they would need water in this particular phase, before being “weaned” eventually and get prepared for the outside world.

Consequences of Low Humidity

Depriving the baby plants of high levels of humidity would affect their growth in a negative manner. Low humidity would force the plant to exert more effort, and thus possibly shortening its life or delaying, or even stunting its growth and development.

Other consequences that we associate with a low level of humidity in the surroundings would include leaving the plant to desiccate, thereby exposing the plant to mold and mildew, as well as infestation of insects like spider mites.

The reason for this vulnerability is because plants that are considerably less moist are more favorable and conducive for other organisms to take advantage of and flourish.

Ways on How to Increase Humidity

Lower Extraction Fan Setting                       

Fans are crucial in every grow tent simply because it allows the air to circulate and be well-distributed by plants. This facilitates the exchange of air inside the grow tent and outside, as fresh air has to be introduced to prevent harmful microorganisms from increasing in number and/or staying in the area.

Having too high speeds for fans, however, would cause the air to dry quicker, instead of giving time for the water vapor around to settle, and thereby be absorbed by the plants nearby. You could also incorporate a humidifier/dehumidifier in your surroundings as well.

If you plan on doing so, make it a point to keep at least a 60% humidity level.

Lower the Temperature of Surroundings

It’s common knowledge that cool air, due to its relative density, would always sink to the bottom. A lower temperature of the surroundings simply means that the air is relatively more moist, thus having a greater presence of water vapor.

This could be achieved simply by reducing the temperature of the heater or increasing the temperature of the air-conditioning system either of the tent itself or the room. Another way for you to do so would be to lower the intensity of the UV light, given that light would facilitate the evaporation of water. This is not a point of concern really, given that young plants don’t really need that much light.

Have Larger Plants inside the Grow Tent as Well

While some people may think that these rob the younger plants of the opportunity to get some air, the reality is that these larger plants actually contribute to the level of water vapor, and subsequently the humidity inside the grow tent once you put them inside, alongside the baby ones.

The reason for this is due to the fact that these plants undergo the respiration process as well, and part of this process is that apart from carbon monoxide, water vapor would be released as well.

Also, bigger leaves would mean more stomata, which would imply that more water vapor would get released as well.

Place Water Sources Wherever Possible

One of the obvious and practical means in order for you to increase water vapor levels would have to be to place water trays where the air intake tubing, or the air holes that are passive are. Another means for you to do so is to saturate sponges and place them near your growing trays.

The heat coming from the UV lamp would slowly evaporate this water, and in the process add humidity inside the grow tent.


While keeping things moist inside is of utmost importance, one of the things you have to keep in mind is that the water you use should be as clean as possible. This is because bad bacteria would cause various diseases to your plants, as well as with you. Make maintenance an integral part of raising your plants, apart from humidity.

Moreover, be careful with adding sponges or small trays of water near fans, given that these are materials that use electricity, and might short circuit when it would come in contact with water.