How Do I Lower the Humidity in My Grow Tent?

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.

AC Infinity CLOUDLINE S4, Quiet 4" Inline Duct Fan with Speed Controller - Ventilation Exhaust Fan for Heating Cooling Booster, Grow Tents, Hydroponics

$89.99  in stock
2 new from $89.99
Free shipping
as of April 14, 2021 10:33 pm


  • Designed to ventilate grow tents, transfer heating/cooling to rooms, circulate air, exhaust odors, and cool AV racks.
  • Features an 8-speed manual controller utilizing PWM. See T-Series for temperature and humidity controls.
  • Mixed flow design combined with a DC-powered motor for a truly quiet and energy efficient performance.
  • Kit also includes corded AC power adapter, installation manual, and all necessary mounting hardware.
  • Duct Size: 4" | Dimensions: 6.9 x 11.9 x 7.4 in. | Airflow: 205 CFM | Noise: 28 dBA | Bearings: Dual Ball

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:

Inkbird Itc-308 Digital Temperature Controller Outlet Thermostat, 2-Stage, 1100w, w/Sensor

 out of stock
as of April 14, 2021 10:33 pm


  • Inkbird Itc-308 Digital Temperature Controller Outlet Thermostat, 2-stage, 1100w, w/ Sensor

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:

ThermoPro TP50 Digital Hygrometer Indoor Thermometer Room Thermometer and Humidity Gauge with Temperature Humidity Monitor

$10.99  in stock
as of April 14, 2021 10:33 pm


  • 【Air Comfort Indicator】Humidity meter with humidity level icon indicates air condition -- DRY/COMFORT/WET, allowing this humidity sensor to ensure you're always aware of changes to your home/household with just a quick glance
  • 【High & Low Records】Accurate hygrometer digital thermometer displays high and low temperature & humidity; Inside thermometer is highly accurate, ±2~3%RH and ±1°F, making it ideal for measuring fluctuating readings like in a greenhouse
  • 【Healthier Home & Environment】Thermometer hygrometer with temperature and humidity monitor ensures proper indoor humidity control has important skin, allergen and other health benefits; Can also be as refrigerator thermometer, freezer thermometer, reptile thermometer, soil thermometer, humidor hygrometer, cigar hygrometer and more!
  • 【Smart Design】Indoor room thermometer features a tabletop stand to place the temperature monitor on your counter or use the magnetic back to attach to a fridge; °F/°C Selector; Powered by 1 x AAA battery (included)
  • 【3 YEARS WARRANTY! REGISTER your thermometer after purchase and INCREASE YOUR WARRANTY COVERAGE FROM 1 YEAR TO 3 YEARS】ThermoPro US Based Customer Service (Phone & Email) 5 Days a Week, reach us at 1877-515-7797 or You don't receive this best in class service from other brands like Acurite, Habor, Lacrosse, Springfield and Taylor

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