Best humidity controller for weed

best humidity controller for weed

Maintaining the correct humidity and temperature in your grow room will make your plants grow faster, produce bigger buds and protect them from mold and disease.

A humidity controller works by automatically switching on and off connected humidity control devices such as humidifiers, dehumidifiers, air conditioners and fans. A humidity controller for weed must be affordable, high quality and capable of supporting a wide range of devices to keep your grow room environment perfect. We researched all the options and compiled this list of the best units on the market today.

Many humidity controllers also allow you to control the temperature of your grow room and we’ve included these in our review.

Click the product links in the table below to read our detailed reviews.

Table of contents


Product comparison table

Product name Image No. devices controllable Type Rating Buy
Inkbird Humidity Controller + Temperature Controller Combo Pack Inkbird Humidity Controller + Temperature Controller Combo Pack 4 Humidity and temp 4.4/5 Amazon
INKBIRD Humidity and Temperature Dual-use Controller INKBIRD Humidity and Temperature Dual-use Controller 2 Humidity and temp 3.8/5 Amazon
Autopilot Digital Environmental Controller with Remote Probe Autopilot Digital Environmental Controller with Remote Probe 4 Full atmosphere 3.3/5 Amazon
iPonic Hydro2Go 614 Grow Room Environment Controller iPonic Hydro2Go 614 Grow Room Environment Controller 8 Full atmosphere N/A Amazon
Inkbird Humidity Controller Inkbird humidity controller 2 Humidity 3.8/5 Amazon
Inkbird ITC-308 Digital Temperature Controller Inkbird ITC-308 Digital Temperature Controller 2 Temperature 4.6/5 Amazon

 

Reviews of the best humidity controller for weed

Inkbird Humidity Controller + Temperature Controller Combo Pack

Buy on Amazon

  • Type: Humidity and temperature control
  • Controllable devices: 4

The Inkbird combo pack includes a separate humidity controller and also the highly rated Inkbird ITC-308 temperature controller.

You can plug 2 devices into each unit allowing you to connect a humidifier, dehumidifier, heater and air conditioner or fan. The probe on both units has a 6.5 ft cable. We think it’s the best humidity controller for weed overall because it provides perfect control over your grow room environment and is very reasonably priced.


INKBIRD Humidity and Temperature Dual-use Controller

INKBIRD Humidity and Temperature Dual-use Controller

Buy on Amazon

  • Type: Humidity and temperature control
  • Controllable devices: 2

The Inkbird dual use controller is a single unit that can control 2 devices, one for humidity and one for temperature. This unit won’t allow a humidifier and dehumidifier to be operated at the same time but if your grow room is too humid or not humid enough, one device might be all you need. The probe also has a 6.5 ft cable.


Autopilot Digital Environmental Controller with Remote Probe

Autopilot Digital Environmental Controller with Remote Probe

Buy on Amazon

  • Type: Full atmosphere control
  • Controllable devices: 4

The Autopilot digital environmental controller is the best humidity controller for weed if you’re looking for full atmosphere control in your grow room.

You can add 4 devices to control humidifiers, dehumidifiers, heaters, air conditioners and fans. CO2 levels can be controlled by switching on and off an exhaust fan and you can also program different temperature and humidity settings for day and night. The probe has a 15 ft cable and another nice touch is the green lighting on the display that’s easy to read but doesn’t cast too much light when it’s dark. This is an amazing device for the money.


iPonic Hydro2Go 614 Grow Room Environment Controller

iPonic Hydro2Go 614 Grow Room Environment Controller

Buy on Amazon

  • Type: Full atmosphere control
  • Controllable devices: 8

If money's no object and you want the best of the best in atmosphere control for your grow room then we highly recommend this unit.

The Hydro2Go 614 can control 8 devices and in addition to humidity and temperature it can control CO2, grow lights, central air conditioning and heating, recycle timers and venting fans. You can even program your own custom devices for 6 of the inputs.


Inkbird Humidity Controller

Inkbird humidity controller

Buy on Amazon

  • Type: Humidity control
  • Controllable devices: 2

If you’re just interested in controlling the humidity of your grow space and are looking for a good quality affordable option, the Inkbird humidity controller is the best humidity controller for weed. The Inkbird can automatically switch between humidify and dehumidify mode and has an alarm when the humidity goes outside the set range you've set. You can plug in 2 devices (a humidifier and a dehumidifier) which can be separately programmed.

Some growers actually connect the dehumidifier function to the fan in their grow room exhaust system which is a great idea. When the humidity gets too high, the exhaust fan comes on and starts venting the humid air from the grow space!


Inkbird ITC-308 Digital Temperature Controller

Inkbird ITC-308 Digital Temperature Controller

Buy on Amazon

  • Type: Temperature control
  • Controllable devices: 2

If you just need to control the temperature in your grow room, this is the unit to get. You can plug in 2 devices to control both heating and cooling and the temperature probe has a 6.5ft fully waterproof cable.


Humidity and temperature gauge

Humidity and temperature gauge

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If you don’t need to control the humidity or temperature of your grow room but want to measure it, we recommend this excellent 2 in 1 hygrometer and thermometer.


What is humidity?

Humidity refers to the amount of water vapor in the air. If the air feels moist, the humidity is high. If the air feels dry, the humidity is low. There are several ways to measure humidity but the the most useful for growers is ‘relative humidity’. Relative humidity refers to the percentage of the maximum possible water vapor being held in the air at a given temperature. For example, 70% humidity means that the air is holding 70% of the maximum possible water vapor.

You can learn more about relative humidity at Wikipedia.

What is the best humidity for growing weed?

Weed plants need different levels of relative humidity during the different stages of growth. Using a humidity controller to set the correct humidity in your grow room will give you faster growth, stronger buds and help stop mold and fungus from attacking your crop.

Humidity for clones

  • The ideal relative humidity for clones is 70 - 80%

Clones are cuttings taken from a mature plant so they initially don’t have a root system to pull in nutrients and water. Until the roots develop, clones get all their nutrients by absorbing moisture through their leaves. High humidity lets clones absorb the maximum amount of moisture through the leaves.

Read our article on cloned weed if you’d like to learn more about cloning.

Humidity for seedlings

  • The ideal relative humidity for seedlings is 65 - 70%

Like clones, seedlings have little or no root system and like high humidity because they need to absorb water through their leaves.

Humidity for vegetative growth

  • The ideal relative humidity in the vegetative stage is 40 - 70%

Weed plants in the vegetative stage get most of their nutrients and water through their roots. However, they also absorb water through their leaves so higher humidity can make them grow faster, especially when they are young and their root system is smaller.

Using your humidity controller to lower the humidity by 5% each week is ideal during the vegetative stage.

Humidity for flowering (budding) plants

  • The ideal relative humidity in the flowering stage is 30 - 50%

Flowering plants are much older and have a fully developed root system so high humidity is less important for fast growth. In fact, high humidity can lead to mold forming on your buds so it’s important to lower the humidity during this stage. If your buds develop mold, they’re ruined and should be thrown away 🙁

Read our guide to growing weed indoors to learn more about the different stages of growth.

Humidity for drying weed

  • The ideal relative humidity for drying weed is 40 - 60%

Drying your buds at a higher humidity takes longer and can increase the chance of mold forming, but it will increase the quality of your weed. For safe drying, keep the humidity lower at around 40-50%.

Infographic - what is the best humidity for growing weed

What happens if my humidity is wrong?

In general, young plants like high humidity and mature plants like lower humidity. If your humidity is wrong during the growing cycle you might run into the following problems.

Humidity too high

  • Mold and mildew forming on leaves and buds which will ruin them.

Humidity too low

  • Slower growth and smaller buds
  • Nutrient poisoning - your plants will absorb as much water as they can through the soil because there’s no water vapor in the air. This can result in them absorbing too much Nitrogen and other nutrients.

How is humidity related to temperature in my grow room?

Temperature and humidity are closely linked. At higher temperatures, more water vapor can be held in the air before 100% relative humidity is reached. This means that if the amount of water vapor stays the same and temperature rises, the relative humidity will drop. In the same way, if the amount of water vapor stays the same and the temperature drops, the relative humidity will rise. Make sense?

The idea temperature for your weed plants is 70 - 80 degrees Fahrenheit (21 - 27 degrees Celsius). If the temperature of your grow room is too low or too high, this can make your plants grow more slowly and will lead to smaller buds.

Our list of humidity controllers includes models that allow you to control the temperature and humidity at the same time.

How to lower humidity in a grow tent

A good quality humidity controller for weed will let you connect all the following devices to lower the humidity in your grow room.

Dehumidifier

Dehumidifiers extract water vapor from the air to lower the humidity. We recommend these two options.

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Exhaust fan

Sucking in air from outside your growing space and circulating it will lower the humidity - as long as the air outside has lower relative humidity than the air in your grow room!

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Exhaust fans work in combination with ducting to funnel the air out of your grow room.

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Air conditioner

Most air conditioners will have the effect of lowering the humidity because they remove and trap the water vapor from the air as they cool it. We recommend this portable one that also has a dehumidifier function.

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 How to raise humidity in a grow tent

A humidity controller for weed should be compatible with all these devices to lower the humidity in your grow room.

Humidifier

A humidifier has a built in reservoir that you fill with water. This water is turned to vapor and added to the air to increase the humidity. There are a few different types but the most common are evaporative humidifiers. We recommend this one.

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