Best Temperatures for Cannabis Plants
Cannabis is a particular plant, there are many factors to consider when attempting to grow a perfect indoor crop, one of them being temperature. If your marijuana plants get too cold, they will begin to grow slowly and eventually die. If the environment is too hot, you will notice slower growth as well as the leaves bending upwards.
Temperature and humidity are entangled with each other, with low temperatures you will lose humidity, and if the temperatures are too high, the humidity levels will rise as well. Now that we’ve covered the basic connections between growing climates let’s dive in and find the perfect temperatures for growing cannabis indoors!
While the ideal temperature for your cannabis plants will depend on their stage in the growth cycle, a general rule of thumb is that marijuana plants prefer room temperature conditions. If your grow room is too cold or hot for you to personally hang around in - your plants are probably not enjoying it, either. The exception this this rule is during the late stages of the flowering phase, where the plant will prefer slightly cooler temperatures.
Keeping track - You have a few tried and true options when keeping track of temperature depending on how much you are willing to invest in your grow. Digital and analog thermometers both work, the latter being easier on your wallet. If you’re looking to invest in the future we recommend a thermo hygrometer which captures and displays current relative humidity and temperature accurately.
Turn it up a notch - If you’re struggling to keep temperatures up there are many options that can help you. A small space heater can be used to increase the temperature in your grow room, but we recommend keeping track of the temperature independently as they can be misleading. A light with higher wattage will surely increase the temperature, as well as a heating mat - both are more expensive options that can be viewed as investments for the continuous grower.
Bring it down - Climate permitting, briefly open a nearby window, keeping track of the temperature as it drops. An AC unit would do the job perfectly but are probably an expensive investment. Setting up your grow cycle so that the lights are off during the day and turn on when the sun goes down is a smart way to do the job, but be sure you can rely on unnatural methods of tweaking the temperature if necessary
The 10th Degree & More - Your light off and light on temperatures should never range more than 10 degrees from each other, the change is too much for a young plant and will severely stunt it’s growth. Anything less than 15°c endangers the plant, it will not die instantly but growing will slow and eventually cease, if temperature is not increased before this happens your plant may not survive.
Temperature may vary slightly from grower to grower depending on climate, location of grow room and strand of marijuana being grown. This plant grows naturally, and mother nature is not an ideal example of consistenecy, so don’t worry too much. The most important part is staying on a strict day-night cycle and keeping your plants above 15°c at all times. Goodluck on your grow - as always, stay botanical.
The Numbers with the lights on:
Seedling - Young: 24°c-25°c Kick start it at a moderate temperature.
Vegetative: 26°c‐28°c Young plants can use the extra heat.
Flowering: 22°c-26°c Not too much higher or your flowers will dry out.
Flowering Finish: 20°c-24°c The cooler temperature helps produce more colorful cannabis as well increasing trichome count.
The Numbers after dark:
Seedling - Young: 20°c-25°c
Flowering Finish: 18°c-20°c