The Best Temperature for Growing Weed

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temperature for growing weed
Author avatar By Derek LaRose
July 30, 2021
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Growing marijuana isn’t simply putting some seeds in the soil and watching them grow. Weed needs nutrients, water, proper growing material, good pH levels, ventilation, pruning, light, and space, just to name a few. So, does the temperature for growing weed matter?

Yes! One of the most important aspects of growing cannabis is the temperature of the indoor or outdoor garden. Weed likes a specific climate to create a reasonable yield without problems. 

Continue reading to find out everything you need to know to create the perfect climate for your marijuana plants. 

Why marijuana growing temperature matters

Temperature for growing weed matters because it’s linked to the health of your cannabis plants. When the environment isn’t quite right, the marijuana crop will have a small yield or be more prone to diseases. 

Some hybrids are fragile and can’t take any extreme temperature changes without dying. Other cannabis strains are heat resistant or more stable. Even then, their maximum yield can be lower if not cultivated in the correct climate. 

The best temperature for growing weed at different stages

The temp for growing weed should be between 65 to 85 degrees Fahrenheit, and marijuana crops prefer specific climates during the different growth stages. 

Temperature for growing weed

Seedling

At the seedling stage, marijuana likes it hot and humid. The best temp for growing weed indoors or outdoors is 70 to 85 degrees Fahrenheit with a 75 to 85% humidity level. 

During this time, the cannabis seeds are growing roots and need to absorb extra moisture because of the rapid growth. Make sure the humidity level never goes over 90%, as this will welcome mold, mildew, and other pathogens.  

Vegetative

The next phase of the weed growing cycle is the vegetative stage. The marijuana growing temperature needs to drop a little to 70 to 78 degrees Fahrenheit during the day. At night, it never should drop more than 10 to 15 degrees. 

In the vegetative stage, you’ll start to reduce the humidity by 5% every week until you get to the range of 45 to 55%. By doing this, you’re preventing the risk of bud rot or damping-off. 

Flowering

The flowering stage is the last part of the marijuana plant’s life. During this time, you should reduce the cannabis temperature again to 68 to 75 degrees Fahrenheit. Keep an eye on CO2 levels, as this can increase the heat throughout the day. 

You’ll need to lower the humidity level an additional 5% each week until it’s at 35 to 45%. During the last two weeks of growth, the moisture needs to be about 30%. Monitoring the humidity level will keep powdery mildew or other pathogens at bay. 

How to control marijuana growing temperature

We’ve gone over the numbers, and now it’s time to tell you how you can achieve the best temperature for marijuana growing. 

You can control indoor cultivating spaces easier because there are fewer elements you have to deal with. If you have central heating, you can use this to regulate the temperature. When this isn’t an option, you can buy a space heater. Remember, lights put off extra heat

With artificial heating, it tends to create a dry environment. Make sure you have a humidifier in indoor gardens. Also, you’ll need some grow tent ventilation within the space to help reduce the temperature or humidity when required. This will also help with how to get rid of weed smell that lingers. 

You’ll have to deal with natural sunlight, wind, rain, clouds, and changing temperature from day to night with outdoor gardens. To regulate the heat within the greenhouse, you can purchase an outdoor space heater. 

Keep the humidity levels in check with a humidifier or by having buckets of water around so that the moisture will naturally be in the air. Use a ventilation system to help regulate the heat on hot and humid days. 

With an indoor or outdoor growing space, you’ll need a high-quality thermometer and humidity checker

Temperature and Humidity in Cannabis Grow Tent

Correcting temperature for growing weed

If there’s an issue with the climate in your marijuana growing area, you’ll need to fix it before any damage happens to your weed plants. 

Temperature too low

When the climate is too cold, it stunts the growth of your cannabis plant, and your yield will be low. If the temperatures drop below freezing, your crops might die. 

If you notice the temp dropping, slowly increase it by turning on your heating system. Then, look for the cause. Maybe there’s a crack in a window or a problem with the ventilation. 

Temperature too high

Marijuana likes the heat, but too much of a good thing can damage the plant. Pathogens are quick to attack vulnerable weed crops. 

Along with that, an excess of heat can hinder the harvest’s ability to perform photosynthesis, which harms the marijuana plant’s growth. Signs of cannabis heat stress are drooping, cupping, or yellowing leaves. 

Temperature and humidity 

Temperature and cannabis humidity levels are linked because the warmer the air, the more moisture it can hold and vice versa. This is important because you need the correct percentage to be balanced to produce a quality marijuana plant.

This table will give you an idea of what to expect at certain temperatures. 

StageTemperatureHumidity
Seedling70 to 85°F75 to 85%
Early Vegetative70 to 80°F60 to 80%
Late Vegetative70 to 80°F45 to 55%
Early Flowering65 to 80°F35 to 45%
Late Flowering65 to 80°F30 to 35%

Temperature and choosing the best grow lights

All lights give off a certain amount of heat. When you’re growing indoors, this is a factor you’ll need to consider.

You don’t want grow lights that give off too much heat because the leaves closest will be at a higher temperature than the rest. Try to look for lamps that don’t change the environment too much.

Ideally, you want the temperature to be consistent in all parts of the room

Final thoughts on the ideal temperature for growing marijuana

When you’re a weed grower, you have to keep in mind many factors. One of the most influential aspects is the temperature of the growing space. 

When the temp is perfect during the different stages, your cannabis crop will yield the proper amount and be less prone to diseases. 

Now that you know all this information check the temperature and humidity levels in your garden. If you haven’t started planting yet, buy some cannabis seeds and use these tips on your way to becoming a successful marijuana grower.

Visit our shop to get the best deals in marijuana seeds! We offer the best genetics and a germination guarantee, so why look anywhere else for your favorite strains?


About the author: Derek LaRose

Also known as Kronic from The Cannabis Kronicles, Derek LaRose is a young ambitious cultivator and a staple educator for indoor cultivation.