The Right Temperature and Humidity is Crucial For Growing Marijuana

Growing cannabis successfully requires tactics, specific tools, and techniques. Knowing what temperature to grow marijuana in is a crucial part of the process. And you usually can’t learn it just by reading growing weed for dummies.

If you want to know how to grow marijuana, it’s important to understand that depending on what cycle of the plant life you are in will determine what temperature your grow room needs to be. For example, cloning requires a higher temperature and humidity than veg rooms, and flowering plants seek their own unique temperature for proper growth. In order to become a master grower, you need to master temperature control of your garden. Plants succeed in specific environments, so what is the best grow room temperature and humidity level?

@Christine_Sclafani educates on climate control of an indoor cultivation.

Temperature and Humidity 

In order to work in marijuana grows, first you will need a thermometer and a hydrometer to properly measure the temperature and humidity in your room. Like most tools, digital is always your best bet, especially one that can give you current readouts as well as high and lows while you’re not inside the room.

Other tools you will need are a heater to heat things up and an A/C unit to cool your room down. These can go inside or outside the grow depending on how much space you are working with. All of these tools will help you to grow marijuana properly.

It’s also important to pay attention to how much your growing room’s misfire levels fluctuate. Humidifiers and dehumidifiers are used to help raise and lower the humidity levels in your room. Large grows can really benefit from a controller that uses a sensor to keep track of temps and humidity and turns on the appropriate appliances to regulate and keep you within your set levels. This info will help you and your marijuana growth.


Indoor Cultivation Clone Room at CCL19-0000071 JVTS, INC in California.

As I mentioned above cloning is done in a warmer environment. This is done because cannabis cuttings root best when they are in warm conditions with high humidity. The cheap trays with clear plastic domes work remarkably well in the early stages in the growing of marijuana. In cool conditions a heat mat should be placed underneath the trays to maintain an optimum temperature of 74-78 degrees F. and relative humidity at 75-85%. No matter where and into what medium you plan to root your clones, keeping warmth and high humidity is top priority. If your clones get cold or dry, they will quickly die. Too much humidity (over 90%) can also cause problems like mold or rot, so cut a quarter sized hole or two in your clear plastic dome. This will allow air movement and circulation for your clones. 

Best Marijuana Grow Room Temperature for The Vegetative Stage

70-78 degrees F is the best temperature for plants during the vegetative stage of growth, when the lights are on for your “daytime”. Once your “night” begins don’t lower your temperatures more than 10-15 degrees cooler with a relative humidity of 45-55%. These settings will allow your plants to convert light into energy for growth. 

READ MORE  How Weed Can Help You Relax
A VEG room inside a large indoor cultivation in Las Vegas, NV.

This is the time when the plants put leaves and branches and expands its root system throughout your growing medium. Be careful because if it gets too cold or too hot, growth will stop. This could cause you to lose your plants altogether. 

The Flowering Stage 

The flowering stage is very important, it is where you little babies become adults. This room should stay in between 68-75 degrees during the day and no more than 10-15 degrees cooler at night.

Inside Cultivation Labs, flowering room in Las Vegas, NV.

Now, if you are supplementing C02 things change just a bit. You can have your temperature up to 75-82 degrees. While the plants are in the flowering stage your relative humidity should be 35-45% and even lower (30%) for the last couple weeks before you harvest. Lowering the humidity will help you combat issues like mold, bud rot, and powdery mildew. 

Drying and Curing 

The drying room is one of the most important rooms in your facility that many novices overlook. This room must be carefully monitored to have a successful crop, especially if you are just learning how to grow marijuana. Keep in mind your plants will be giving off a large amount of moisture, into the room as your plants dry. It’s crucial to pull wet out of the room and keep air circulating in the room without having fans blowing right in your hanging branches. Fans directly blowing on the plants can dry them out prematurely resulting in a harsh taste and burn.

Another thing to consider, is dry places like Colorado struggle to extend their drying with humidifiers, while growers in more humid climates like Northern California use dehumidifiers to help pull water from the air. This is done to help avoid mold on their buds. 

The final stage of the entire growing process requires harvesting, curing and drying the buds out. Hanging plants upside down in the ‘Curing Room” is the traditional way to do it.

So, what’s the ideal temperature? The drying room should stay in between 65-74 degrees Fahrenheit with your humidity between 45-55% in a dark ventilated area. It’s very important to keep a close eye on your drying room as cannabinoids, terpenes, and flavonoids can evaporate and be released at temperatures above 80 degrees. This will affect the scent, flavor, and potency of your buds. 

After 6-10 days of drying your branches should snap instead of bending, and the buds should feel like popcorn dry on the outside. This is when you can cut the buds off the branches and put them into jars or bags to begin the cannabis curing process. Cure your cannabis buds in a cool 68-72 degrees Fahrenheit room that is nice and dark. 

Now you know

Those are the ideal temperatures for all the different types of rooms within an indoor grow. It’s extremely important to closely monitor your building’s temperature in order to grow that top shelf marijuana the world has come to love. So, whether you enjoy your weed in a pipe, a bong, a joint or a vaporizer, you now know how important temperature and humidity really when growing marijuana indoors.