The Best Temperature & Humidity Controllers For Grow Rooms

temperature and humidity controllerNow that you’re growing your own cannabis, the humidity and temperature in the grow room are two of the most important things to consider. In order to grow a quality crop, you must have control over the humidity and temperature your plants are exposed to.

This means you will most likely need a grow room air conditioner, grow room dehumidifier, and watering systems. All these have to be in sync with each other all the time.

Sound complicated? It really isn’t. With the right equipment, which we’ll tell you all about in this article, it is going to be pretty simple for you to sustain the perfect environment.

With the right controller, you can put your humidity and ventilation equipment on autopilot. Take care to follow all local laws and regulations when buying this equipment!

Top 7 Temperature And Humidity Controllers

The devices below monitor humidity and temperature levels, and carbon dioxide levels in some cases. Usually, they plug in a separate timer, not directly into your master controller.

The Autopilot Master ControllerControls temperature and humidity levels 24/7
Titan Controls 702850 Saturn 4 Digital Day and Night Environmental Controller with PhotocellManages a dehumidifier, fan, a CO2 device, and a nighttime device
Holmes Cool Mist Comfort HumidifierIncreases humidity
Holmes Warm Mist HumidifierIncreases humidity
Ivation GDM20 Thermo-Electric DehumidifierLowers humidity
LTL Control Element 2 Environmental ControllerMaintains temperature, light sensor, measures humidity and CO2 levels
Extech 445713 Big Digit Indoor/Outdoor Hygro-ThermometerMeasures temperature and humidity

1. Humidity Controller with Remote Sensor: The Autopilot Master Controller

The Master Controller from Autopilot lets you control up to 4 different units. This all-inclusive controller’s LED indicators show if something’s gone wrong immediately. You can set different temperature and humidity levels for nighttime and daytime, so that your plants get the perfect environment at all times. If you have a power outage, the battery backup will make sure your settings don’t go back to default.

Advantages of the Master Controller from Autopilot:

  • Can be used with up to four devices
  • Has separate day and night settings
  • Has a battery backup for power outages
  • Great value for your money

On the downside, this product does not have a warranty. Its largest size temperature probe is three inches, and the maximum Amperage load is 14.5. You won’t be able to use it if your grow op is larger.

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2. Humidity Controller for Any Size Grow Room: Titan Controls 702850 Saturn 4 Digital

The Titan Controls Saturn 4 is an analog controller that manages a dehumidifier, fan, a CO2 device, and another piece of equipment that should only operate at night. It uses a photocell to determine when nighttime is for your cannabis.

This product also has a remote sensor on a 15-foot cable, which makes it possible for it to be planted in the soil.

Top Features

  • Usually dispatched within 3 to 5 weeks.
  • One button allows you to change between three different operating modes
  • 3-year warranty
  • Shipping Weight: 2.2 Kg

On the downside, this unit can be a bit expensive for a beginner.

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3. Holmes Cool Mist Comfort Humidifier with Digital Control Panel, HM1865-NU

Still wondering how to raise the humidity in your grow tent? This is a big issue indeed, especially if you live in a hot, arid place like a desert. Such environments can definitely make raising weed a challenge just because your average daily humidity might not be high enough.

Cannabis needs around 70% as a seedling and around 40% at least when you’re ready to harvest. This can be difficult in places like Phoenix and Las Vegas, where the humidity can be as low as 20% on average a day. But this doesn’t mean you can’t grow weed if you live in Vegas.

Of course, you can pour more water on your weed to help raise moisture levels, which does work as a temporary fix. You could also set up several open containers of water around your grow tent. However, this might not suffice either. If you live in a dry, arid place, you should definitely invest in a weed humidifier. You can run it on a timer so it can operate while you’re playing.

Types of Humidifiers

There are two kinds of humidifiers —cool mist and warm mist – and both may affect the temperature in the grow tent. Holmes is a very famous grow equipment brand – their Cool Mist Comfort Humidifier runs up to 48 hours on a single tank so you don’t have to fill it very often. It has four settings, ensuring that your plants won’t get too much moisture. When it reaches the desired humidity, it switches itself off, and it also has a timer.

The Holmes HM1865-U Digital Cool Mist Humidifier’s controls are easy to operate, facilitating the maintenance of your desired comfort level. With a 2.4-gallon output and 1.5-gallon tank capacity, it’s perfect for a big grow room. It also has a 16-hour timer and LCD digital display.

Top Features

  • Shipping weight: 4 kg
  • Runtime: Up to 48 hours
  • Humidistat with LCD display
  • 16-hour programmable on/off timer
  • Uses hwf65 c replacement filter
  • Filter treated with Arm & Hammer Baking Soda and Antimicrobial Protection

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4. Temperature Controller for  Growing Plants: Holmes Warm Mist Humidifier HWM6008-NUM

The Warm Mist Humidifier HWM6008-NUM, another top of the line product by Holmes, can run up to 24 hours on a single tank, albeit not being quite as fancy as the previous product. If you live in a humid place where it rains a lot, this product is for you. Growing pot in high humidity means you’ll have to watch for mildew and mold issues the whole time.

If this is the case, you will lose a lot of produce to mildew problems. If you want to lower the humidity in your grow tent, either get an AC or upgrade your ventilation system. The third option is investing in a dehumidifier. A fan is not enough.


  • Item Weight: 10 Kg
  • Product Dimensions: 40.4 x 73.7 x 37.1 cm
  • Shipping Weight: 2.1 Kg

By and large, this is the best humidifier out there, and it’s great value for money. The tank lasts two nights without needing a refill. The night light is very pleasant, and the noise level is completely bearable. There are no issues with the cleaning.

Breathe With Ease

This is also one of the few models on the market producing noticeable steam. When you use the warm mist, the room stays warm and feels really nice and cozy. The electric static will be gone, there will be less dust flying around, it will even get easier to breathe.

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5. Ivation GDM20 Thermo-Electric Dehumidifier, 1100 Cubic Feet

The Ivation GDM20 Thermo-Electric Dehumidifier works silently because it has no moving parts. It condenses water from the air and drains it into the transparent cup at the bottom.

It shuts down when the cup is full until you empty it. This is great value for money and perfect if you have a small grow tent. Don’t forget to monitor humidity levels, because it could be taking too much out of the air. We would recommend an indoor thermometer as well.

  • Thermo-electric Peltier module Technology
  • Small size
  • High Power
  • No Moving Parts
  • Reduces humidity in small areas and tiny spaces like a closet, basement, crawl space
  • Can be used in RV, Boat, Car, Home, Bathroom, Bedroom
  • Collects around 16 fl. oz. per day (500ml) at 86°F (30°C) 80%RH.
  • Water reservoir capacity: approximately 20 fl. oz.
  • Height: 8.75 Inches
  • Dimensions: 8.75″ x 5.3″ x 5.75″ (14.6 x 13.5 x 16.4 cm)

It really is quite a bargain and is usually delivered within 10 days.

It’s much quieter than standard dehumidifiers, compact and lightweight, making it easy to move from room to room and between areas as needed. Its power input is 9V 3A. The shipping weight is 1.2 kg.

Additional Information

In contrast to old-fashioned, compressor-based dehumidifiers, this one utilizes advanced Peltier technology. What does this mean? This silent technology has a wide variety of amazing benefits and quiet operation is just one of them. It also enables producers to fit such a powerful and effective dehumidifying system into such a small package.

The machine is lightweight with a longer life cycle and does not need any moving parts to function. It is very, very easy to use. All you need to do is check that the removable water-collection reservoir has been installed securely, and click it in in any room or area of your premises that you want to get less humid. This includes, of course, your grow room or tent!

How well does this item work? As the product’s name would suggest, it is suitable for spaces up to 1,100 cubic feet. It’s perfect for small laundry rooms, basements, cellars, attics, and even cars and boats, but not for huge premises obviously, so large-scale growers won’t have much use for it. There will be around 8 ounces of water left in the tank at the end of a day of 80% relative humidity and 86° Fahrenheit. It can hold approximately 16 ounces or 2-days’ worth of dehumidifying action, sparing you the effort of having to empty out an overflowing water tank every day.

Indicator LED Lights Up When Tank Is Full

As with all other Ivation products, it is equipped with flashing light. An indicator LED lights up to remind you to empty the tank out when it’s full. A 9v DC power adapter is included, and the peak of power consumption is 22.5. This makes this item extremely efficient and reliable, not to mention its convenient dimensions (see features above).

I also have this unit in a small room after a lot of cooking or boiling water or in the shower space after I take a shower. At first, we thought it would draw more out of the air, but this wasn’t the case. The unit dispenses warm air and the AC adapter heats up relatively quickly. The window units then work harder to keep the room cold. We recommend unplugging the adapter to let it cool now and then.

It does make a dent in the humidity even in bigger spaces for what you are going to be paying. We would assume it is more suitable for premises equipped with central or forced air cooling. If you decide to get it, buy one size bigger than the cubic feet of the space where it is going to be used. It would be great in a closet or storage room for maintaining controlled climate.

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6. Best Digital Temperature and Humidity Controller: LTL Control Element 2 Environmental Controller

Here is another controller for smaller sized grow rooms that is great value for money. It does not cost as much as many other options, yet works very effectively and boasts many of the same features. The Element 2 Controller can control your CO2 generator, inline fan or dehumidifier and all other daytime devices of your choice, plus one nighttime unit. This controller works particularly well when you have a separate timer for your lighting system.

The Element 2 by LTL Controls is an excellent solution for maintaining temperature, light sensor, humidity, CO2, and nighttime devices within the growing area. It can control 1 cooling device, 1 dehumidifier or humidifier, and 1 CO2 device controlled by a recycling timer apart from the nighttime device mentioned earlier.

It can also display the maximum and minimum recorded temperature and humidity readings.

This product is developed using high-quality UL/CE listed components to ensure years of operation and features a 3-year warranty.


  • Package size: 7 x 9 x 12 inches
  • Shipping Weight: 14 pounds
  • Produced by LTL Controls

Other information

The item has no electronic or digital ballast, boasts heavy-duty internal construction, a superiorly engineered circuit board and high-quality UL/CE listed components to guarantee years of operation.

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7. Extech 445713 Big Digit Indoor/Outdoor Hygro-Thermometer

Finally, let’s give hygrometers and thermometers some attention, because we all know that they are really important too. We’ve decided to feature Extech because of its fabulous two-in-one solution – it is both a hygrometer and a thermometer – and is also a trusted manufacturer of measuring equipment.

This is one of my favorite devices. The 445713 hygro-thermometer shows you indoor and outdoor temperature and humidity. It features a min/max function so you can see the difference over the period that passed since your last active measurement.

Prop the 445713 inside or outside your grow tent or hang it on a nail. Stick the probe into the soil in the shade beneath your weed. The display is big and clear, so it is easy to view even if your light is weak.


  • Max/Min stores and recalls high and low measurements for all 4 parameters
  • Outdoor sensor with 35 in. (89cm) cable
  • Built-in stand and wall mounting bracket included
  • Displays indoor and outdoor temperature and humidity
  • Accuracy: +/-1.8 degrees F and +/-5% humidity

A fellow grower bought one of these about three years ago and recently noticed that the remote sensor probe was not showing the right humidity level values, so he contacted the manufacturer to ask about buying just the probe and replacing it himself, because it looked like it was just attached to the cable with a small screw.

The Customer Service representative that handled his request told him that she would send him a brand new Extech 335713 item for free even though she did not have easy access to a replacement probe right at that time. Apparently, the manufacturer stands fully behind all their products and take good care of their clients and their clients’ requests. I was very impressed, to say the least.

If only all equipment producers had customer service with a policy of handling requests this way.

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How to Choose the Best Temperature & Humidity Controllers

humidity control grow roomGrow room controllers and grow cabinets make creating an artificial environment for your weed easy and simple. This is because your room or garden is completely isolated from the outside world – no light gets in or out.

A grow light controller is hence worth investing in. Grow cabinets are especially nice for seedlings because they won’t take up a lot of vertical space. If your crops are larger, make sure that doors and windows are covered and sealed.

When it comes to growing cannabis, temperature and humidity are crucial factors. This is because they set the stage for fast growth and proper development of the buds. Marijuana likes about the same temperature as humans, so it’s probably comfortable in your grow room if you are.

Younger Plants

Younger plants like higher temperatures because they can absorb more moisture from the air through their leaves. Cooler temperatures help to reduce the risk of mold and mildew inside of the moist buds when they start producing flowers. This is something to keep in mind when choosing your grow room AC.

If your grow room is kept too cold, your plant growth will be stunted, and the plants can die if it’s freezing. Alternatively, they may become extremely bushy or long and spindly if it’s too hot. To cool down your grow room, increase the ventilation inside of the room or switch to LED lights. To make it warmer, you can use extra lights, heating pads or HID lights, which generate more heat than LEDs.

Humidity Is Important for Grow Operations

There’s no underestimating the significance of humidity for cannabis growers. The best indoor humidity is neither too high nor too low. If it’s too high, the plants might start suffering from mold and mildew in the flowering stage. They are ruined if you see or smell any mold on them. To increase humidity, you can increase the temperature with less ventilation or lighting or use a misting humidifier to increase moisture in the air.

If it’s too low, on the other hand, you need to improve your ventilation with a higher powered fan or more fans. Another way to raise the humidity in the grow room is by using a hydroponics-grade portable dehumidifier.

There is a risk of the plants consuming too much nutrient solution because they are not able to get enough moisture through their leaves. This can result in nutrient burn and cause the plants’ leaves to wilt and go brown. Then the leaves get dry and crunchy, and your yield drops.

Growth Stages, Temperature, and Humidity

In the cloning (very young plants) stage, the ideal temperature is 74 to 77 degrees with no temperature drop at night, and the ideal humidity – 70% to 80%.

Vegetative (rapid growth) stage: 75 to 85 degrees day time, 65 to 75 degrees night time, humidity: 40% to 70%.

Flowering (developing buds) stage: 65 to 80 degrees day time, 60 to 75 degrees night time. Max humidity: 40%.

Our Final Review

Regardless of how many plants you have, you should design your grow setup in advance for the best results. Buy better quality or higher capacity products than you think you’ll need so you won’t need to replace them sooner than you think.

Use LED lights instead of HIDs to save money. You’ll spend more initially but you will spend less on electric power and you won’t have to replace bulbs for up to a decade down the road. What’s more, you won’t need to cool down your grow tent because of the lights.

Check how much weed is legal in your area so you will be able to plan the relevant precautions, like a high-quality ventilation system with a carbon filter that reduces odor. Use a bud trimmer to harvest more quickly and easily once your plants have matured.

One Last Tip

Don’t throw the weed plant’s leaves away. Instead, use them to make cannabis oil. The types of cannabis oil are medical marijuana oil, oil for edibles and butane hash oil. The last kind is very dangerous and we don’t recommend trying to make it at home.

The second kind, on the other hand, is very easy to make. It is a key ingredient for brownies and other dishes. It is not to be smoked or applied on the skin. We hope you enjoyed our article about the best temperature and humidity controllers for growing weed!

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