February 27, 2024

Humidity Levels and Apt Grow Temperatures: Your First-Hand Cannabis Guide

In your cannabis growing journey, a healthy harvest is not just the result of a lot of hard work, careful attention, and patience. You need to get a good grip on specific tactics and techniques to ensure robust resinous buds.

This is all the more important if you are going to have your marijuana cultivation indoors. You need to understand in-depth about temperature, and relative humidity levels of your grow room.

Relative Humidity And Temperature

The amount of moisture the air can contain at a particular temperature is known as humidity. Cooler air is less humid than warm air. Therefore, relative humidity increases as the warmth of the air increases.

Is this confusing for you? Don’t worry.  I will lay down a comprehensive guide for you to understand the best room temperature and relative humidity for growing marijuana.

The growth stage your marijuana plant is in would determine the kind of temperature and humidity you need to provide. The plants that grow from seeds require specific humidity and temperature during the vegetative and flowering phases. Also, a plant growing from a clone would require more humidity and temperature than the seedlings.

Let me explain the temperature and humidity requirements of all these phases of growth of a marijuana plant.

Growing Cannabis from Clones: Best Humidity Levels And Temperature

Cannabis clones like warm temperatures and high moisture in the air to start rooting.


I like to use inexpensive plastic trays which have clear domes on them to root these cuttings. If the weather is chilly, I prefer putting these trays over a heat mat. The mat enables me to maintain the ideal temperature.

The clones ideally prefer 75 to 85 percent relative humidity and 74 to 78 degrees Fahrenheit temperature.


Take care not to let the clones become too dry or too cold; otherwise, they might quickly die.

Over 90 percent humidity will cause the roots to rot or develop mold. Making a few quarter-size perforations in the plastic domes over the tray should prevent this problem. Those holes will make way for some air circulation around the roots. The roots will get space to spread well.

Humidity Level And Temperature Requirements At The Vegetative Phase

The vegetative stage of a cannabis plant is when it starts growing branches and leaves. Its root system also expands.

Appropriate temperature and humidity allow the plant to turn light to the energy it needs to grow at this stage.

Keep the grow room temperature within 70 to 78 degrees Fahrenheit at this phase during ‘daytime’ or when the grow lights are switched on. When you switch the lights off during the night or the dark period, keep the temperature about 10 to 15

degrees cooler than the day. Maintain the relative humidity of about 45 to 55%.

If the temperature becomes too cold or too hot, the plant will stop growing, and if continued for a longer period, you might lose them. Higher humidity can also lead to the development of mold or root rot.

However, if you are a new grower, you might need some time to perfect the art of providing the correct humidity and temperature. You might want to check out the beginner seeds sections of the top online marijuana seeds stores like i49 for hardy and forgiving plants that can sustain a fluctuation or two.

Flowering Phase Temperature And Humidity Levels Requirements

The cannabis plants get ready to produce buds in this stage.

Temperature and humidity level plays a key role in enabling the plant to grow flowers filled with resinous psychoactive trichomes.

These trichomes are the ones that lend flavor, test, and potency to the weed.

During the daytime, keep your grow area temperature around 68 to 75 degrees Fahrenheit. Lower the temperature to around 10 to 15 degrees during the dark period. You can also take the daytime temperature 75 to 82 degrees Fahrenheit.

During the initial days of the flowering phase, the relative humidity must be between 35 to 45%. Once the flowers develop, the humidity must be gradually lowered. During the last two weeks of harvest, keep the moisture level around 30%.

If you forget to decrease the humidity, you will likely face issues like mold, bud rot, or powdery mildew (PM). This can be your worst nightmare because it would result in a failed harvest.

Humidity And Temperature Requirements Of Drying And Curing Process

Drying area temperature and moisture content should also be monitored carefully.

The hanging buds will release quite a lot of moisture as they dry. The wet air must be carefully exhausted and circulated in the drying space.

However, if you are using fans for air circulation, place them so that they blow air in between the hanging stems and not directly onto them. This will prevent premature drying, a major cause of weed burning harshly and producing cough-inducing smoke.

You might face challenges in providing an appropriate drying time for your buds if you have an arid climate. You need to prolong your drying time using humidifiers.

Suppose your climate is more humid than dry; use dehumidifiers to extract wet air from the drying room. High humidity will make the buds develop mold.

A quality drying room should be dark, well ventilated with humidity between 45 to 55 percent and temperature between 65 to 74 degrees Fahrenheit.


Do not let the temperature fall below 80 degrees or diminish the fragrance, taste, and potency. Warmer temperature will cause the high inducing cannabinoids, terpenes, and flavonoids to evaporate.

The hanging stems should snap between your fingers after 8 or 10 days of drying if you provide the correct temperature and humidity.


The buds that are ready to be cured would feel dry on the outside.

Snip the individual buds and fill 75% of a glass mason jar with them for the curing process. Curing should also be done in a dark spot with a cool temperature. The ideal curing temperature should be between 68 to 72 degrees Fahrenheit.

Now that you have a low down of the ideal temperature and humidity for each growth phase, here are the techniques that I use to measure and change these factors.

Techniques for Measuring And Changing Temperature And Humidity

Thermometers and hygrometers are the two pieces of equipment you need to measure your growing room’s temperature and humidity levels. The digital thermometers and hygrometers are the most accurate ones to provide you with the readings. They also provide the highs and lows of the entire day.

If you want to increase the temperature, a heater will be of use. An air conditioner would help you lower the temperature of your growing room.

You can install all this equipment inside your growing room or outside, depending on its size. You must also consider the range of fluctuation of temperature and humidity that the space goes through.

A humidifier will help you raise the humidity levels, whereas a dehumidifier enables you to decrease the moisture levels.

If you have a large growing space, you can buy a controller that has a sensor built in it. This equipment will help you in keeping track of temperature levels and humidity. It will also turn appliances to regulate the temperature and humidity levels when they are not in tandem with the ideal levels.

Final Thoughts

I believe that I have provided everything you should know about creating the optimum temperature and humidity levels in this first-hand guide.

You should bookmark this article as this will help you in every growth phase of your marijuana babies.

In addition to temperature and humidity, you also need to take care of the watering and nutrients to ensure a spectacular growth.

I hope you enjoy your marijuana-growing journey immensely. Here is wishing the best of buds for you.

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