Indoor Temperature and Cannabis

The indoor climate for growing cannabis has an enormous affect on the quality, yield, and health of your cannabis plants. Ideal conditions help the plants thrive and reduce problems with pests and pathogens.

Maintaining an ideal environment for your grow rooms can be a difficult task. The weather can affect it and so do internal conditions, such as the heat that is generated by your lighting.

It is extremely important when planning out your grow room that you consult an expert on growing cannabis and not just rely on architects and electricians. Cannabis growing experts will offer suggestions/solutions for keeping your grow rooms as close as possible to ideal conditions.


The ideal temperature for growing cannabis indoors would be between 62°F to 72°F with lights off and between 68°F to 80°F with lights on.  Use the lower end of the range for seedlings, as they haven’t yet formed a root system robust enough to uptake water. Lower temps reduce the amount of moisture lost through their leaves. As the plants get larger — vegetative stage, you can aim for the higher end of the temperature range. You lower temps again during flowering for better trichome production.

Ideally, you don’t want your temperature to vary by more than 12°F between your lights on and lights off periods, but the plants do better when it is about 10 degrees cooler during the dark period.

If your temperature is too low, the evaporation rate through your leaves will be lower and cause the plants to uptake fewer nutrients. As cannabis plants lose moisture through evaporation, they take up more water and nutrients to replace what is lost. (This process is called transpiration.)  If they are taking up fewer nutrients, their growth can be stunted.

If your temperature is too high, the cannabis plants will grow more slowly. Having temps above 80°F in the “bloom rooms” can reduce the potency and smell of your buds.  Excessive temps also make the plants more susceptible to spider mites, powdery mildew, root rot and nutrient burn.  This is especially true if the humidity is too high as well.


To make sure that you can better control the temperature in your grow area, you should do the following things:

  1. Make sure your grow area is really well insulated to protected from extremes of cold and heat from the weather.
  1. Ensure that you have adequate heating and cooling systems to maintain your ideal temperature.
  1. Place your seedlings and clones in a separate grow room from your other plants so that you can give them the special temperature and humidity they need.

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