Skip to main content

Having the best conditions for growing marijuana can increase your yield and potency. There are a lot of intricacies of indoor marijuana growing, but the ambient temperature is one of the main focuses of indoor growing. So, what is the best temperature for plants to grow in?

What is the perfect environment for growing plants and producing high-quality cannabis? When growing cannabis, temperature can be manipulated for optimal results. This guide will show you how temperature affects your cannabis and how you can control it.

Optimal Temperature For Vegetative Cannabis

It's important to note that cannabis plants are not special. They can tolerate a wide range of environments and still produce dank marijuana. However, when growing cannabis indoors, the plants need optimal conditions to make up for the lack of actual sunlight that is so vital to plant health.

Lighting solutions exist to simulate real life, but indoor plants still end up less hardy than outdoor cannabis plants regardless.

With that in mind, utilizing temperature control to help your indoor plants thrive is imperative for indoor marijuana growing success. So, what temperature do plants grow best when in a vegetative state?

The best weed grow room temperature is somewhere around 70-80°F during the day cycle. This is the best temperature for the vegetative stage because it optimizes growth in the plants with efficient photosynthesis. Varied temperatures that are too high or low will lower the rate of photosynthesis, and the growth rate of the plant itself.

When the lights are off, it's best to have a temperature that is around 10° lower than the daytime temperature. So if you keep your grow room at 75° when the lights are on, aim for 65° when they are off.

Optimal Temperature For Flowering Cannabis

In outdoor growing operations, cannabis plants flower in the Autumn when temperatures start to drop. This ideal flowering temperature is somewhere around 65-75°F. The same 10° differential from light and dark is optimal as well, just as when in a vegetative stage.

This flowering temperature allows terpene and cannabinoid maturation. Too high temperatures can degrade sensitive terpenes, which will affect the flavor, aroma, and high of cannabis.

Manipulating your grow room temperature for flowering can also bring out purple, blue, and pink colors in the buds themselves when the temperature is low enough.

cannabis temperature being taken inside a cannabis garden

What About Best Humidity For Growing Weed?

It'd be irresponsible to talk about temperature without addressing humidity. Temperature and relative humidity are intertwined and produce different effects when one, or both, are too high or low.

The optimal relative humidity is around 40-60% in the grow room. Staying closer to the lower end is important during flowering. Grow room temperature and humidity must be controlled together for optimal cannabis production.

The best temperature and humidity for growing weed will be the temperatures fit for the life stage of the growing plants and a stable humidity to avoid risk for mold and mildew.

Learning how to control temperature and humidity in a grow tent will determine whether you produce dank bud or have a throwaway batch that amounts to nothing but a learning experience.

Problems From Temperatures Too Low For Indoor Marijuana Growing

When the marijuana grow room temperature drops too low, plant growth will be stunted. Drop even lower and the plants could die from freezing. While this is unlikely to happen in an indoor grow operation, avoiding moderate lower temperatures is still important.

A grow tent temperature that is too low can promote mold growth, especially if humidity is high as well. This is why you see mold growth in the flowering cycles when temperatures are low and humidity is high.

The perfect grow tent temperature will not stunt growth from too low of a temperature, whether night or day. Remember, the 10° differential between night and day is optimal. Don't let it get too cold when the lights go out.

Problems From Too High Temp For Indoor Marijuana Growing

Having a grow room temperature too high is much more common for indoor cannabis growers. The best temp for growing weed avoids the environments that diseases and pests thrive in.

A marijuana growing temperature above optimal will increase the risk for pests like spider mites and diseases like powdery mildew.

Cannabis grow lights can put off a lot of heat that can create hot pockets directly below the lights. Proper air circulation and ventilation are crucial when the grow lights are on.

Keeping your cannabis grow room cool enough will be an ongoing job for indoor marijuana producers.

How To Control The Temperature In Your Grow Room

Learning how to lower grow room temperature and humidity will make or break your indoor ganja grow. You can find the ideal temp for indoor grow room operations with a variety of appliances:

  • Air Conditioner
  • Space Heater
  • Humidifier
  • Evaporative Cooler
  • Dehumidifier
  • Fans

Finding out how to control temperature and humidity in a grow tent using these appliances is pretty easy if you monitor your room with thermometers and hygrometers.

Air conditioners and evaporative coolers lower the temperature. Evaporative coolers also raise humidity levels.

Space heaters heat the room. Combination units that control humidity can raise or lower humidity based on the relative humidity of the cannabis grow room.

Fans don't change the temperature. Instead, they keep air circulating and help you avoid hot and cold spots.

You may need some or all of these for optimal indoor marijuana growing conditions.

Cannabis Temperature FAQ's

What is the ideal temperature for cannabis seedlings?

The best temperature range for cannabis plants is between 68°F and 77°F (20°C and 25°C). This range of temperatures helps roots and leaves grow in a healthy way. It's also good for plants to keep the humidity high, between 65% and 70%.

What is the best temperature for growing cannabis indoors?

During the day, when the lights are on, cannabis plants do best when the temperature is between 70°F and 85°F (21°C to 30°C). A drop of 5 to 10°F at night is normal and more like what happens in nature. Cooler temperatures, ideally between 65°F and 80°F (18°C and 26°C), help buds grow and make the plant more potent during the flowering stage.

How does temperature affect cannabis growth?

Temperatures that aren't in the right ranges can slow plant growth, lower yields, and make buds less good. Heat stress can make plants wilt, and high temperatures can also make pests and diseases more likely to spread. Low temperatures can slow down digestion and growth, which could cause plants to grow less and produce less.

What is the ideal temperature for growing cannabis outdoors?

While outdoor cannabis plants are somewhat more adaptable, they generally prefer daytime temperatures between 75°F and 85°F (24°C to 29°C). Nighttime temperatures should not drop below 60°F (15°C) to avoid stress. It's important to consider local climate and weather patterns when growing outdoors.

There are over 300,000 jobs in the cannabis industry. CTU trained me for one of them!

marijuana extraction course - Johanna Rose
Makes $24.50 @ THC +

What temperature should I avoid to prevent heat stress in cannabis?

Cannabis plants can get heat stress if they are left out in temperatures above 85°F (29°C) for long periods of time, especially if there is a lot of humidity. Dropping leaves, turning yellow, and maybe even stopping growth are all signs. In hot places, reducing heat stress can be helped by making sure there is enough air flow and using shade or cooling systems.

What is the ideal temperature for drying cannabis?

When cannabis is ready to be dried, it should be between 60°F and 70°F (15°C to 21°C) and 45–55% humidity immediately after harvest. These conditions help the buds dry slowly and evenly, which keeps the oils and cannabinoids inside. If you dry something too fast, it can make harsh smoke, and if you dry it too slowly, mold can grow.

How does temperature affect cannabis drying and curing?

Keeping the right temperature while drying and curing weed is very important for keeping its quality. If it's too hot, the buds might dry out too quickly, losing their taste and potency. On the other hand, mold can grow when temperatures are low and humidity is high. Keeping the temperature and humidity at the right amounts will make sure that the drying process goes slowly and evenly, which is important for making high-quality, strong cannabis.

Get Your Cannabis Temperature Right!

Achieving the best temperature for marijuana is ideal for growing the bar possible bud indoors. Managing your grow box temperature with a variety of appliances is your best bet to ensure good indoor marijuana growing conditions. If you want to learn about growing weed indoors and how to optimize the process, keep learning with us here at Cannabis Training University!

Luis Cordova
Luis Cordova

Luis Cordova is a distinguished author, and renowned expert in cannabis cultivation, who possesses a Master's degree in Plant Biotechnology and Pharmaceutical Science. As a valued contributor to highly esteemed publications such as Cannabis Training University and Maximum Yield Magazine, Luis has emerged as a trusted source of guidance and knowledge in the cannabis industry. Having written thousands of informative articles, Luis is widely recognized for his comprehensive expertise on cultivating cannabis, both indoors and outdoors.

Enroll Now