How Do I Lower the Humidity in My Grow Tent?

As an Amazon Associate I earn from qualifying purchases.

Sometimes grow tents can increase to less than ideal humidity levels. It’s important to combat this in a smart and cost effective way. Below you’ll learn the best ways to achieve an ideal grow tent or room humidity level.

Lowering the humidity in a grow tent is a great way to exercise control of the growing process. We have written a great DIY grow tent guide if you’re looking to build your own tent system and control even more of the growing process.

Ways to lower the humidity in a grow tent

1. Get a dehumidifier

Here’s the most obvious suggestion. A dehumidifier works by drawing moisture out of the surrounding air. Dehumidifiers collect the extracted water in a container to be emptied, unless you can use gravity or a sump pump to continuously dispose of water through a floor or sink drain.

Our favorite dehumidifiers have that “continuous” option where the water is continuously extracted from the surrounding air and runs through a hose. That hose should drain down into a drain (gravity is your friend). You may have to buy a hose and connector separately, depending on which dehumidifier you buy.

If you can’t do the continuous option on your dehumidifier, the only option is using the equipped water container. This can be a bit tedious because you’ll need to take the container of extracted water and dump it out yourself.

We’ve written a detailed post showcasing what we found to be the best grow room dehumidifiers. There you’ll find some excellent options for any budget from around $30, up to $150+.

2. Get an exhaust fan

Increasing air flow will help lower your grow tent humidity. There’s a reason bathrooms have exhaust fans, and it’s to lower humidity so mold does not set in. Similarly, any good grow tent setup should have an exhaust fan to help move air out, while a different vent can allow fresh air to enter the tent.

Exhaust fans for hydroponic grow tents are primarily for blowing the warm air out of the growing area. You can also use fans to blow cooler air inside your growing area, which is something commercial setups are know for using.

Some of the nicer grow tents come with a kit that includes an exhaust fan, in other cases you’ll have to purchase your own separately. Here’s an excellent choice if you’re looking for an exhaust fan. For a deeper dive check out our post of the best inline fans for grow tents.

[content-egg module=Amazon template=item next=1]

3. Increase ventilation

Humidity will increase in areas that are hot and not well ventilated. Adding vents to your tent or room can help to introduce cooler outside air which can normalize the inside temperature. This can go hand in hand with our exhaust fan suggestion above which forces the air movement. Ventilation also helps introduce fresh air into your growing area.

4. Get a humidity controller

This is something you may not be as familiar with. A humidity controller will connect to your humidifier and dehumidifier to help them work together and keep your grow room levels consistent. All you have to do is set the range and you’re good to go. These can run you around $40. You can spend a lot more on controllers that control other things like fans and CO2 levels.

Here’s our favorite humidity controller for grow rooms or grow tents:

[content-egg module=Amazon template=item next=1]


How do you measure the humidity in a grow room?

Every grow room should have a hygrometer to measure the room/tent’s humidity level. A hygrometer is the fancy name of a humidity meter. These are most commonly battery operated with a digital display, making the results accurate and easy to read.

Along with displaying the current humidity expressed as a percentage, some hygrometers also display the range of the humidity level over a set amount of time. You’ll also notice that most hygrometers also show the current temperature and range since those can correlate with the humidity level.

For an excellent and inexpensive hygrometer, check out our top pick below:

[content-egg module=Amazon template=item next=1]


High humidity is the enemy of the hydroponic gardener because it can stop your plants from reaching their full potential. High humidity can create mold which will harm your plants. We want you to grow the best possible plants you can grow, and hope our handy guide will help you lower the humidity inside your grow tent or grow room.

High Tech Gardening
Logo