marijuana growing temperature

What is the Ideal Marijuana Growing Temperature?

Temperature is an important factor in growing all kinds of plants including cannabis. There is ideal marijuana growing temperature to follow across the different growing stages: seedling phase, vegetative phase, and flowering phase. It’s important to get to know the different growing temperatures to provide the best growing environment for your plants.

Good old common sense

Cannabis plants need temperatures that are similar to what humans need but sometimes, a bit warmer but not too dry.  When growing cannabis indoors, use old-fashioned common sense. If you feel warm or hot or you feel very cold then it’s likely that your plants are also experiencing the same thing.

If your indoor growing area feels very cool or too warm then you must consider changing the room’s temperature and humidity as these factors go hand in hand.

What is the ideal marijuana growing temperature that plants need?

Cannabis plants require specific temperatures from 70 to 85 degrees Fahrenheit or 20 to 30 degrees Celsius during the day or when the lights are on. When it’s nighttime or when the lights are off, cannabis plants require colder temperatures.

When it comes to young plants in the growing phase, the area must be slightly warmer at 70 to 85 degrees Fahrenheit or at 20 to 30 degrees Celsius. We will get to know more temperature ranges as we go along this article.

In the flowering stage, cannabis plants require cooler temperatures from 65 to 80 degrees Fahrenheit or from 18 to 26 degrees Celsius.  This temperature benefits plants in the blooming stage as this prevents the development of molds. Mold can dramatically affect your yields as this can consume your buds overnight. Mold development in your garden can lead to costly problems; severe infestations can ruin all your hard work.

During the flowering stage, some cannabis plants require a cooler environment as this brings out lovely bud colors. Cold temperatures will also bring out the natural color, density, trichome production, and smell of cannabis. Experts suggest placing your plants 10 degrees Fahrenheit or 8 degrees Celsius temperature difference between daytime and nighttime temperatures.

Consider the following when managing temperature inside your growing area

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Temperature control must be carefully considered indoors. To do this, you need proper ventilation, efficient fans, ACs or coolers, and correct lighting.

  • Ventilation should be carefully planned. Consider that hot or warm air should be removed from the growing area as this can greatly affect your plants. Hot air rises and thus you need correct fan placement to remove it.
  • We recommend using a combination of two fans. One fan is the outtake fan, this will remove warm air from the room and thus it should be installed on the top section of the growing area. Usually, expert growers install a larger outtake fan to efficiently remove warm air from the room and this is placed somewhere near the ceiling. Meanwhile, a smaller intake fan is placed somewhere near the floor of the room. This will help take cool and fresh air in the room and replenishes warm air continuously.
  • Ventilation should be efficient and seamless to prevent heat and humidity build-up inside the growing area. Inefficient ventilation will lead to countless problems that can cost the blooming phase and harvest phase of your plants.
  • Using air conditioning units and evaporative coolers can effectively reduce high temperatures. An AC will quickly improve room temperatures and will also work no matter how hot or how cold it may be. Meanwhile, evaporative coolers are also very efficient in improving the temperature of a warm room but will only work if the room’s humidity level is below 30%.
  • To find the right air conditioning unit to cool your growing room, verify the actual size of the room by multiplying the length to the width of the room. Multiply the answer to 25 BTU; the product is the right AC capacity to efficiently cool your room or growing area.
  • The type of strain also matters if you want to grow cannabis indoors. Some strains can withstand too much heat or a cooler environment so you must choose well what kind of strain you want to cultivate.
  • The correct light schedule also matters if you want to maintain the correct growing temperature. If the day is too hot or it’s too cold at night then adjust your lighting timer to compensate. Changing the time that your grow lights are switched on will help you improve day and nighttime temperatures. Improving lighting schedules will even help you save money on electricity as you don’t need to use electricity during nighttime.

Get to know the other factors to consider when growing weed indoors. Select the best marijuana grow book!

The effects of low temperature on cannabis plants

Growing areas in cooler temperatures can slow down your plants’ growth. When temperatures are lower, around 60 degrees Fahrenheit or lower, your plants’ growth will slow down while very cold to freezing temperatures can shock or kill your plants. Meanwhile, other plants may still grow during the cold stress-free but yields may be affected.

There are also cannabis plants that are very susceptible to mold and therefore, higher humidity and temperature must be avoided. Mold may also develop after ice or frost start to melt and water is all over the growing area.

And just like what was mentioned, cooler temperatures and significant reductions in temperature can lead to the development of purple leaves and can diminish photosynthesis. Plants that are cultivated in the wild will survive but will not grow as healthy and as productive as those plants in the right growing environment.

The effects of high temperatures on cannabis plants

Very high temperatures or temps higher than 80 degrees Fahrenheit during the blooming phase will slow down the growth of buds. The heat will also lead to airy and very loose buds and may also lead to low bud smell and potency. Cannabis may also be prone to different problems during warm temperatures like the onslaught of pests, mold, and mildew, and root rot.


The ideal marijuana growing temperature is simply not too hot and not too cold. If you feel warm then adjust the temperature to cool the growing area. If you feel chilly, chances are your plants are also struggling. Always be mindful of the correct growing area temperature.

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