Best Temperature and Humidity Controllers

If you are looking to produce quality cannabis, it is no secret that you need to understand everything about maintaining humidity and temperature. Monitoring the humidity and temperature changes in a grow room is essential since they can either make or break a cannabis garden. Whenever you are not keen on changes in humidity, your plants may face issues like rotting buds or powdery mildew. While many home growers may hesitate the need to purchase a humidity and temperature controller since some may be pricey, it is but a necessary investment to make to prevent your plants from dying and have a better harvest.


However, before committing to any controller, it is best that you understand the relation between humidity and temperature and how it affects your cannabis plants in the different growing phases. Humidity is the percentage of the moisture in the air versus how much the air can hold at that given moment. The saturation of air depends on the temperature and moisture content meaning that the grow room temperature is responsible for the increase and decrease of humidity. When the grow-room temperature is too high, the air can, therefore, hold more water thereby setting the stage for an increase in humidity. On the other hand, low temperatures in the grow room reduce the amount of water vapor the air can hold hence having low humidity.

As you can see, it is of critical importance for you to acquire the right tools necessary to monitor humidity and temperature levels for your plants. Regardless of whether you are on a budget or you have substantial money to invest, you need to get the best hygrometer and thermometer to help control your grow environment. You can also find an all-in-one hygrometer and thermometer to make your work easier. Here are the BEST TEMPERATURE AND HUMIDITY CONTROLLERS you will find in the market.

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The Top 5 Temperature and Humidity controllers in the Market

Inkbird AC 110V Digital Pre-Wired Outlet Dual-Stage Humidity Controller

The Inkbird HUMIDITY CONTROLLER proves to be a compelling choice for the regulating of humidity in the grow tent. It has a plug and play design making it user-friendly and easy to operate. Its humidity calibration is also easy to read, you only need to set the humidity you desire, and the device will work on its own. The controller allows you to switch between humidification and dehumidification automatically. It has an alarm feature that goes on when the humidity level exceeds or goes below the set value.

Titan Controls Day/Night Temperature Controller

Since the temperature in a grow room should be different when the lights are on and when they are off, you require a device that can help you identify the difference. The Titan Temperature Controller can help you control the temperature in your grow-room according to the time. You can set the temperature between the range of 55 and 95 degrees Fahrenheit. The controller is an ETL –listed product meaning that it passed in the quality control test and is approved for use commercially. It comes with a plastic casing that offers protection to its internal components against dust and moisture. It comes with a three-year warranty.

Titan Controls Digital Environmental Controller w/ Carbon Dioxide (CO2) Timer

The Saturn 5 Titan Digital Environmental Controller is one of the best models that we would recommend to anyone that wants to get one device that can control all the environmental elements. The device controls not only humidity but also temperature and the level of carbon dioxide. It has an LCD that allows the user to monitor the temperature and humidity changes in a grow tent. It comes with a 15 foot remoter sensor that detects the temperature, humidity, and CO2.  You can as well set day time and night time temperature levels.  It has a data logging feature that allows you to set the highest and lowest humidity and temperature level you require in the grow room. It comes with buttons that are color-coded for easy programming. The device is made with a plastic enclosure to help extend its service life by protecting the internal components from moisture, dust and other environmental factors.

Extech 445713 Big Digit Indoor/Outdoor Hygro-Thermometer

The Extech Hygro-Thermometer is one of our most favorite tools from Extech, a brand that is well known to provide excellent measuring tools. The hygro-thermometer can measure both the indoor and outdoor humidity and temperature. It has an accuracy level that is down to + or – 1.8 degrees Fahrenheit for temperature and + or – 5 percent for humidity. It features a maximum and minimum function that can help you view the difference in temperature and humidity over the period through since you last actively made a measurement. It has a large LCD screen with two sections for easy reading of both temperature and humidity. It comes with a 35-inch cable to help with providing outdoor temperature and humidity measurements. The device comes with a low battery indicator that lets you know when you need to replace the battery.

Bjerg Instruments Indoor/Outdoor Thermometer and Hygrometer

If your preference is using antique devices, the Bjerg Instruments Thermometer and Hygrometer is our best recommendation to that aspect. It features an analog interface and comes with a glass lens and metallic enclosure. It is 8 inches in diameter, and you can use it for both indoors and outdoors. It has a 5.5-inch diameter face that is easy to read with the thermometer gauge at the top and the hygrometer at the bottom. The temperature display allows you to read the measurements in both Celsius and Fahrenheit.

What are The Ideal Conditions for Growing Cannabis?


You are solely responsible for creating the right environment to grow cannabis. However, for you to do that, you need to identify the right conditions for marijuana in terms of humidity and temperature. The ideal temperature you need to attain when growing cannabis should be between 68 and 77 degrees Fahrenheit. You need to identify the difference in temperature when the lights are on and off and make sure that it does not exceed 18 degrees Fahrenheit.

An increase in temperature levels to 80 degrees Fahrenheit leads to a subsequent increase in the amount of water and fertilizer your plants need. Instead of the buds growing more abundantly, they eventually stretch. You should set the temperature at high during the vegetative stage of cannabis growth and keep reducing the temperature once you get into the flowering and harvesting stages.

Here is a look at how the temperatures should be;

  1. Clone/Seedling Stage – 66 to 77 degrees Fahrenheit.
  2. Vegetative Stage – 70 to 80 degrees Fahrenheit.
  3. Flowering Stage – 67 to 78 degrees Fahrenheit.
  4. Harvesting Stage – 65 to 76 degrees Fahrenheit.

When looking at humidity, the best range should be between 40 to 70 percent. Any higher or lower could have significant damages to the plant. You should however always keep in mind that the exact humidity level is dependent on the stage of growth of the plant. The sprouting stage requires more humidity than any other stage. The humidity level gradually reduces down each level of growth due to several reasons. One, when there is high humidity during the flowering stage, your marijuana starts to get moldy. Here is a quick reference as to how humidity affects the different stages of cannabis.


They require an optimal relative humidity of 70 percent.

Since clones do not have a fully developed root system to help with the uptake of water, it depends on the leaves ability to get water from the air. However, this is only possible if there is a high humidity level. By ensuring that the level of humidity is high, you can increase the chances of the development of the clone roots and eventually its overall growth.

Seedling and Vegetative Stage

They require an optimal relative humidity between 40 and 60 percent.

During the seedling and vegetative stage, cannabis plants require a pleasant environment to grow a lot of leaf mass. When there is high humidity, the leaves take in water from the air until the roots mature enough. During this period, a low level of moisture can only slow down the growth of the plants. The main idea is to create a warm environment that is similar to spring or summer. You should not give the seedlings a humidity dome unless it becomes too dry. As the seedling mature and change to young plants, you should maintain the relative humidity around 50 percent. Whenever you see wet spots on the plant leaves, the relative humidity then is too high and should be lowered.

Flowering Stage

They require an Optimal Relative Humidity between 40 and 50 percent.

Immediately the plants get into the flowering stage it is imperative that you lower your humidity to around 40 to 50 percent. During this stage, the cannabis already had an extensive root system that can fulfill and deliver its water needs. Even so, they are still able to absorb water using the leaves making it vital to maintain a low level of humidity to prevent the formation of molds and mildews. The fungi can appear inside or on the buds or colas, and if not taken care of immediately, it may spread to all your plants destroying your harvest. You should drop the humidity level during the last 2 to 3 weeks before harvesting to increase the production of resin providing you with extra-potent buds during harvesting.

Drying Buds

They require an optimal drying humidity of 55 percent.

By keeping the humidity in the range of 50 percent, your buds can start to dry at a reasonable pace that is not too quick. The humidity range helps to prevent the formation of mold for a beginner. However, cannabis growers with more experience tend to dry their buds with a high level of humidity making to take more time, but the results are of high quality. It is essential to be cautious when drying with high humidity since a slight mistake can lead to the formation of bud molds. When drying your buds, you should allow air to circulate freely. However, avoid blowing it directly over the buds since that will quicken the drying rate.

Tips to Help You Control the Relative Humidity of Your Grow Room

One of the essential requirements for the successful growth of marijuana is by ensuring that your growing environment is carefully sealed and insulated. If your grow room is in a commercial building, we would advise using a foam insulator or any other material and make a thick barrier that separates the grow room from the external environment. By sealing and insulating your grow room, you gain the upper hand in controlling your marijuana environment, and you can prevent external factors such and humidity, light and wind from affecting your marijuana plants.

Frequently Asked Questions

What is the right temperature for a grow tent when the light is on?

You should always look to changing the temperatures of your grow room if it feels cold, humid or dry. The preferred temperature for cannabis growth when the lights are on is in between 70 to 85 degrees Fahrenheit.

What is the required humidity level for a grow room?

During the beginning of the cannabis flowering stage, you should lower the humidity to around 40 and 50 percent, and as the plants gradually get to the harvesting stage, the humidity should be lowered down to 30 percent or less.


Lighting is a crucial factor in the growth of marijuana. Too much of it, however, may lead to an increase in temperature in the grow room. You need to acquire an air conditioning system that is not too large or too small to keep your grow room at the right temperature. If you get an AC unit that is too large, it will consume tons of electricity and create an environment where the temperature and humidity fluctuate occasionally. When the AC unit is too small, the grow room temperature increases to a very uncomfortable level creating a disastrous environment for plant growth. When there is too much humidity in the grow-tents, your cannabis plants may start to develop while mold on the leaves affecting the quality of the yields or even begin rotting. When the humidity is too low, the cannabis with have stagnant growth and lose the ability to receive the necessary nutrients for its survival.

All in all, the wrong temperature and humidity levels in a grow room will make plants to suffer, pest and diseases become prevalent, the yields lessen and last, but not least, the plants may eventually die. We hope that this guide will help you make the best decision in selecting GROW ROOM CONTROLLERS that can help you get the best out of your cannabis plants.

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Bowden draws from over a decade of home growing experience as well as consulting for small-scale and hobbyist-level growers. He has written hundreds of articles, thought pieces, and tutorials about growing cannabis at home

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