Perfect Temperature and Humidity for Grow Room

Controlling the atmospheric conditions in a garden can have a significant effect on the quality of your yield. All types of growers are continuously trying to calibrate their farming methods to achieve the best results. Being able to achieve the perfect temperature and humidity for a grow room is among some of the most important factors to consider. 

As a savvy gardener, you have to learn about all the ins and outs associated with making the perfect growing area for your plants. There is a multitude of techniques and consumer market products which are suitable for the process. To ensure your yield is of high quality, you have to ensure that you are as close as possible to these products and techniques. 

When evaluating the atmospheric conditions of a garden, most people think about aspects such as temperature and humidity. Plants require specific requirements to grow and survive. Aside from moisture and heat, factors such as light intensity and airflow are also crucial.

There are various tools you can use to evaluate your environment and be better equipped for managing plant growth and development. Among some of these critical tools include:

  • Thermometer – This is a temperature regulation tool, which you use to measure how cold or warm the environment is in the garden.
  • Hygrometer – you can use this tool to measure various aspects including the water vapor and air quality
  • Infrared thermometer – these types of thermometers use a unique detection device to measure surface temperatures. While they are not necessary tools, they are useful in determining leaf temperatures. The tools will also provide you with additional insight into regulating environmental conditions.

How to Control Environmental Conditions in The Grow Room

Temperature and humidity are among some of the critical factors to consider when it comes to controlling the conditions in a grow room. Light intensity is also an equally important factor, but this is a topic discussed on another growers’ guide.

As far as temperature and humidity go, being able to control both of these two factors is crucial towards the yield of your plants. 

Once you have the proper tools for making environmental measurements, you can start implementing the changes in the grow room. In this case, the two main areas of focus are the temperature and humidity levels. 

Inevitably, your grow room will face various environmental fluctuations. These fluctuations can happen throughout the grow space, and specific areas inside the grow room. The conditions might also occur at particular points within the day, or perhaps all through the season as weather patterns change.

Regulating Temperature

The temperature in a grow space has an impact on the metabolic rates of the plant. The porous openings on the plant determine the intake of C02, heat, and light. Simply put, stomata are an inbuilt AC unit for plants. As the stomata open and produce water vapor, they transpire and remove freshwater from the roots up.

That said, when the temperature in the environment is low, this might slow down the plant processes, and this might hurt their overall growth. However, when the climate is warmer than usual, these systems work harder, and the stomata might close up. If the stomata close up, the water and nutrient delivery decreases and the plant fails to cool down as required. 

You can regulate the temperature by manipulating for critical factors. They include:

  • The light – perhaps the most significant impact on the garden temperature relates to the type of light you are using, and the amount of heat it produces. Different grow lights will provide varying levels of heat and signatures. All these also depend on the size of your space, which in turn affects the room temperature. Incandescent lights such as metal halides and compact fluorescent lamps can produce lots of heat in small areas. That said, even some LED bulb brands can also produce heat. 
  • Airflow – controlling the flow of air is an efficient technique for regulating the flow of hot and cold air in a grow room. The flow of air is vital in ventilation, especially in regard to the elimination of bad quality air from the grow room. More so, airflow is also crucial for canopy plants, which require top-notch ventilation and air quality.

Tools for Regulating the Flow of Air in Growroom

  • Fans and ducts – these are tools for controlling the flow of air. The fans direct the flow of air to a specific direction, and ducting helps to direct air in and out of the grow space.
  • Inline fans – these are tools that help to remove air from the garden. The oscillating and stationary fans direct fresh air through the garden. Even more, they also have ducted hoods, which can remove the hot air that often fills the canopy.
  • Air Conditioners – while an air conditioner adds to the overall cost of managing your grow room, it’s an essential component, especially for commercial growers. The benefit for growers is that the consumer market has various types of air conditioners available. You can go for the smaller versions if you feel you already have ballooned energy costs. 
  • Heaters – during the winter seasons, or if you perhaps have plants that are sensitive to the cold, then you will require a good heat. Similar to air conditioners, you can easily find some of the best and affordable heaters on the market.

Balancing the System

It can be challenging to find the right amount of temperature and humidity because these components have effects on each other. Thus, turning up the dehumidifier might reduce the humidity levels of your grow space, but might also increase the temperature levels in the area. This might, in turn, require you to turn on the AC unit, and everything is ready to go!

Depending on the severity of the seasons in the area, you can schedule the light cycles in relation to the temperature levels outdoors. During the summer, the increased temperature levels mean that you have to regulate the temperature levels of your grow rooms for the best results. The same applies for winter when you might have to adjust the light cycle such that night time plants don’t get affected by the cold.

The Best Temperature Levels for Growrooms

To maximize the efficiency of your grow room, try to determine the best temperature range for similar grow rooms within your area. Usually, factors such as the type of plant, play a significant role in choosing the proper temperature levels. 

For most annual plants with fast growth rates, and initial temperature range to operate average between 71-82°F (21.4-26.8°C). Furthermore, these plants will prefer growing at the upper end of this plant range. This temperature range applies to both the flowering and vegetative stages.

Growers that have a climate-controlled room can leverage the temperature as a starting point when trying to determine the best operating range. During the process, consider evaluating how air temperature can impact the root mass of your plant. Also, many indoor gardens use hydroponic systems or plant containers, and these plants are prone to even minute changes in the temperature. 

For this reason, growers must be aware that high-temperature levels mean that the root mass is also exposed to high temperatures. The growers with climate-controlled can consider experiments with plants over the seasons, to determine a suitable threshold level. You can then use this information to come up with a temperature schedule for the best growth results. 

For most plants, the best temperature range for vegetative growth is also suitable for fruiting. However, some varieties prefer to grow in environments that are too cool.

Broadly speaking, most plants perform best at 77°F (25.9°C), while some prefer the temperature to be at an average of (81-86°F).

Perfect Humidity for Grow Room

You have probably read it or perhaps come across the statement, grow plants prefer humidity levels of over 60%. That said, what can one do when the hygrometer shows a lower reading ( such as at 30 or 40%? What happens when the leaves start drying and curling like taco shells? You apply all DIY treatments, but nothing is useful – thus, which solution is best in this case?

What is Relative Humidity?

This refers to the amount of water vapor in the air at a specific temperature level. Various sources contribute towards the water vapor levels in the atmosphere. These include animals perspiring, evaporation, plants breathing, and more. The relative humidity level affects the growth of plants because it affects the movement of water through the plant.

Why is Low Humidity Bad for Plants?

Plants consume a lot of water, but a small amount of it remains for developing new cells. Most of the water passes through the plant and is sucked up through the roots. The water then passes through the vascular structure, and then through tiny holes referred to as the stomata. Aside from nutrition, plants require lots of water to serve as a coolant. 

Dry and low humidity levels might create what is referred to as a high vapor pressure deficit. This means that the interior of the leaves on the plant has full moisture. Thus, this would affect the ability of the plant to remove waste products and its nutritional process as well. Such conditions also cause the plant to work harder, which hurts the result of the yield.

As such, most growers prefer starting the seedlings by using propagators. These are tools that help to seal the moisture to create the perfect humidity levels for the environment. Thus, your small and tender seedlings can focus on growth without having to overwork their small rooting systems. That said, what happens when your plants outgrow the propagator?

Increasing Relative Humidity Inside a Grow Tent

Using a grow tent is perhaps one of the most effective ways to create the perfect environment for your plants. You get the freedom to dedicate a specially customized grow area to suit the yield of specific plants. Being able to control the temperature levels 

Humidity refers to the amount of water vapor accumulated in the air. There are four vital resources to consider for controlling the humidity levels. They include:

  • Dehumidifiers – the dehumidifiers remove moisture from the air. These tools are often used in indoor grows spaces, because plants in small areas can release lots of moisture. Thus, a humidifier can be an easy and convenient way to track the humidity levels in the grow room. 
  • Humidifiers – a humidifier can provide a constant flow of water vapor for plants that require specific levels of water vapor. These are tools that leverage cold water to produce a mist that releases water through space, and also improves the levels of moisture.
  • Water – if you don’t have a humidifier, consider using a mist spray bottle to produce additional moisture. 

NB: Using these resources effectively relates to the size and space within the grow room. These are also factors to consider when purchasing components such as air conditioners.


Unfortunately, temperature and humidity control can only be as good as you are informed as a grower. You have to learn about the correct principles and methods behind growing specific plants. This way, you can give the plants an ideal environment to grow and survive, thus improve the result of your yield. A grow room is perhaps one of the most effective approaches for creating a perfect environment for your plants. 

Broadly speaking, most plants perform best at 77°F (25.9°C), while some prefer the temperature to be at an average of (81-86°F). Using an informed approach is your best bet at achieving the best grow room results. 

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