Best Humidifiers for Grow Tents & Grow Rooms

Plants lose water through their leaves, and the drier the air, the faster they lose it. Raising humidity slows that loss, which helps seedlings and clones in particular.

A humidifier is a convenient and inexpensive way to raise humidity in a grow tent. Pair it with a hygrometer or humidity controller so you know the actual level.

Too much humidity is a bigger risk than too little in flowering, because dense buds are prone to mold. This guide is for adults 21+ growing where it is legal.

Choosing the best humidifier for grow room plants or your indoor garden doesn’t have to be a difficult proposition. Here is how you might consider finding the best option for your set-up.

PRODUCT	TYPE	BEST FOR
TaoTronics Cool Mist Humidifier	Ultrasonic cool mist	Small tents
Homasy Cool Mist Humidifier	Ultrasonic cool mist	Longer run time
iTvanila Ultrasonic Humidifier	Ultrasonic cool mist	Adjustable nozzle
Pure Enrichment MistAire Humidifier	Ultrasonic cool mist	Simple dial control
Everlasting Comfort Ultrasonic Humidifier	Ultrasonic cool mist	Large tank

Tank size, run time and coverage claims vary by model and change over time, and some of these brands come and go from stores. Check the current maker listing before you buy.

Choosing Humidifiers for Grow Rooms

TaoTronics Cool Mist Humidifier

The first pick is the TaoTronics Cool Mist Humidifier. TaoTronics products have had patchy availability in US stores, so check that it is still sold before you plan around it.

It comes in two pieces: the base and the tank. You also get an instruction manual for operating the unit and a warranty card.

The unit is made of plastic with a shiny white finish and a clear blue tank that allows you to see the water level. Underneath the tank, there is an included cleaning brush.

There are three mist levels for controlling the amount of mist that is added into your grow room at once.

When you turn the unit on, it will start up on the lowest setting. Press the mist control (+/-) button to increase the mist.

You can control the direction of the mist by turning the nozzle. To turn on the night light, press the nightlight sleep button.

How fast it raises humidity depends on your tent size and how much air your exhaust fan moves.

Things We Like:

• Quiet operation
• Tank large enough for overnight running
• Three mist settings
• Night light LED display features the water level
• The unit shuts off automatically when the tank is empty

Things We Don’t Like:

• You may notice a strong plastic smell during unboxing

Homasy Cool Mist Humidifier

If you are looking for a high-capacity humidifier that will keep your grow tent humidified for longer, look no further than the Homasy Cool Mist Humidifier.

It has a large tank, so you refill it less often.

It has a sturdy design with a white base and a colorless tank that makes it easy for you to observe the water level.

It runs quietly. A filter does not make ultrasonic mist "clean"; using distilled water and cleaning the tank do far more.

What we liked most about this humidifier is the easy to refill top design. You don’t need to take the unit apart in order to refill water.

Things We Like:

• Large capacity tank
• Quiet operation
• Top-fill design
• Shuts off automatically when it runs out of water

Things We Don’t Like:

• May be difficult to clean
• May leak water on the non-waterproof surface

iTvanila Ultrasonic Humidifier

This is one of the finest ultrasonic humidifiers that you can use in your grow tent. It has a large tank and runs quietly. You can also program the unit to shut itself down automatically.

It has an adjustable mist knob, which allows you to adjust the moisture in your grow room. It has a nozzle that rotates 360° to deliver a mist to all corners of your grow tent.

Place it on a raised, waterproof surface and aim the mist away from plants and lights so leaves and fixtures stay dry.

Things We Like:

• Large water tank
• Low noise operation
• 360° nozzle
• Auto shut off when low water levels are detected

Things We Don’t Like:

• May be difficult refilling the tank

Pure Enrichment MistAire Ultrasonic Cool Mist Humidifier

Keep the air in your grow room moisturized with this Cool Mist Humidifier from Pure Enrichment. It slows water loss from leaves when the air is too dry.

It has a large tank and an adjustable mist knob. It produces cool mist, not steam.

It runs long enough to cover a full day on a lower setting, and it includes single and dual mist nozzles.

This unit can be rotated 360° and it has the auto shut off technology that prevents the system from burning out when the water level drops below the minimum.

Things We Like:

• Long run time on lower settings
• Mist dial allows you to adjust output
• Easy to customize moisture output with the single and dual mist settings
• Whisper quiet operation
• Turns off automatically when the water level drops

Things We Don’t Like:

• It may leak, soaking wooden floors
• May suffer from condensation

Everlasting Comfort Ultrasonic Cool Mist Humidifier

The Everlasting Comfort Ultrasonic Humidifier is a large-tank model that suits growers who don't want to refill often.

It runs quietly and steadily.

You don’t need to check the water level frequently because the humidifier will turn off automatically when it detects low water levels.

It is filter-free. Tap water works, but in any ultrasonic unit it leaves a fine "white dust" of minerals on leaves and gear, so distilled water is better.

It has an easy to use analog control knob. You have to turn the knob clockwise for minimum mist setting, and anticlockwise for maximum mist setting.

Things We Like:

• Large capacity tank
• Filter-free design eliminates filter replacement costs
• Shuts off automatically when low water levels are detected
• Built-in handle allows for easy removal of the tank

Things We Don’t Like:

• Doesn’t have a clear water tank
• May leak water on the surface

Things to Consider

The type of humidifier you choose should have the capacity to suit your grow room. Output per hour and tank size matter most.

You cannot conclude whether or not a humidifier is suitable for your indoor garden by its price. Here is what you need to know to find a high-performing humidifier for your plants.

Type of Mist Produced

Your first consideration is whether you want a cool or warm mist unit. Both units provide similar advantages, but there are some important differences.

• Cool Mist Humidifiers

Cool mist units add moisture without adding heat, which suits warm grow rooms. There are two major forms of cool mist units: ultrasonic and evaporative.

Evaporative units normally use a fan to push dry air through a filter, and the water disperses into the atmosphere of the room.

Read Also: Best Inline Fans

Evaporative humidifiers release far fewer minerals and microbes than ultrasonic units, per the EPA. They can still grow microbes in standing water, and they tend to be noisier and need filter changes.

Ultrasonic types make mist by vibrating the water.

The water moves from the reservoir through a valve to a small chamber containing a transducer. In the chamber, water is vibrated endlessly.

The vibration breaks the water into very fine droplets, which leave through the nozzle. The EPA notes ultrasonic and impeller units generally disperse the most minerals and microorganisms, so use low-mineral water such as distilled water.

• Warm Mist Humidifiers

Warm mist units boil water and release the vapor. They add heat, which can help in a cold room.

They can cause burns, so keep them away from children and pets. They also use more electricity.

Grow Room Size

You have to be certain that the best humidifier you buy can fill the grow room sufficiently. A unit that is too big for the indoor garden may lead to condensation on the sides.

Most grow tents are small, so a small or medium home humidifier is usually enough. An oversized unit can over-humidify the space.

Growers usually run higher humidity for seedlings and clones and lower it as plants mature, keeping it lowest in late flowering. A review of cannabis diseases recommends dry indoor conditions to reduce Botrytis bud rot. A humidity controller that switches the humidifier on and off makes this easy.

High humidity also invites mold on walls and gear. The EPA advises against humidifying homes above 50% relative humidity, so keep grow-room moisture contained and have a dehumidifier ready.

Pick a tank big enough to run through the night at your usual setting.

Read Also: Best Grow Boxes

Ease of Use and Maintenance

You need to invest in a humidifier that is easy to refill. Therefore, choose a model with an easy to remove the water tank.

Keeping the unit clean stops it from spraying bacteria and mold. The EPA recommends emptying, drying and refilling portable units daily and cleaning them every third day.

Choose a humidifier that is easy to disassemble, clean and dry. Follow the maker's cleaning directions; without them, the EPA suggests 3% hydrogen peroxide, rinsed out well.

Some brands may claim that their humidifiers have antimicrobial and antibacterial properties, but such claims are not reliable.

If you are allergic or asthmatic, buy a model that will not interfere with your health, since you will be breathing the air in the grow room when you’re checking up on the unit or your plants.

Final Words

You want your grow room humid, but not wet because standing water should never be in your grow. Therefore, choose a good quality humidifier that will disperse a fine misty spray. But, there are other humidifier features you have to consider.

We found out that it is extremely important to match the size of the humidifier to the size of your room.

An oversized humidifier can cause condensation and mold. Overall, choose a unit that is easy to operate and clean, and run it with distilled water.

Sources

• Use and Care of Home Humidifiers, US EPA
• Emerging diseases of Cannabis sativa and sustainable management, Pest Management Science (via NIH PMC)