Unlike humans, plants do not have the ability to generate their own heat. For this reason, plants rely entirely on their outside environment for warmth. Specifically, a plants heat comes from external light, temperature, and level of evaporation. Each stage of the cannabis plant’s growth cycle has its own sweet spot for these external environmental factors. Keeping temperature and humidity at their optimal levels will greatly impact the overall quality of your cannabis flower.
Keeping your plant at an ideal temperature is also essential to its health. If your plant is too hot, its growth may be stunted. External temperatures that exceed 80°F will prevent your cannabis plant from producing tits maximum quantity of flower, as well as hindering its potency and aroma.
Below you will learn more about the importance of temperature, and how to get it right for each stage of the growth process.
Why temperature is so important to your cannabis plant:
You may already know the process of photosynthesis. Plants contain something called chlorophyll, which gathers energy from sunlight in order to convert carbon dioxide from the outside air into sugars like fructose and glucose. These sugars are then transported internally throughout the plant to places like its roots and flowers. Without these sugars, these parts of the plant cannot grow.
This is why it’s so important to ensure your cannabis plant is properly distributing its internal sugars. If your cannabis plant’s flower is not receiving enough sugar, the flower will not grow to its full potential.
Looking for a good thermometer with humidity readings to track the temperature of your grow room? This one has an app to monitor remotely as well:
Plants have difficulty properly distributing their internal sugar when they’re subjected to temperatures less than 68°F (20°C). In these temperatures, your plant’s internal sugars will not flow properly, stressing out your plant and reducing its capacity for growth. Improper temperatures are especially hard on young plants, stunting their growth.back to menu ↑
Temperature for cannabis plants based on their growing phase:
Your cannabis plant will respond differently to temperature depending on their maturity, and what phase of the growth process they’re in. Here’s what temperature you should expose your plant to at each phase of your plant’s life.back to menu ↑
Best temperature for seedlings and clones:
68 – 77°F (20-25°C) with high levels of humidity.
The ideal temperature for your seedling is roughly the same as the ideal temperature for a clone. This is because, like seedlings, clones are still developing their root system. Therefore, clones need to emit a healthy amount of transpiration until their roots are fully developed. Transpiration in this context means water vapour that a plant emits from its stoma. Getting your plant to emit proper levels of transpiration requires a lot of humidity. This is why many growers use a humidity dome in the beginning of their clones’ lives.back to menu ↑
Best temperature for vegetative stage:
68 – 77°F (20-25°C) with about 70% humidity.
Your plant will need more humidity the younger it is. As your cannabis plant progresses into maturity, it will require less humidity. While your plant is in the vegetative stage, keep it in a temperature range of 68 – 77°F (20-25°C) with about 70% humidity.
While your plant is in the darkness phase of its light cycle, slightly reduce your external temperatures. This slight drop of temperature during your plant’s darkness phase will help your plant to grow. Just be careful: don’t let external temperatures drop below 59°C (15°C).
The older your plant gets, the colder temperatures—and drier air—it can withstand.back to menu ↑
Best temperature for flowering stage:
Once your plant enters the flowering stage, it’s best to keep a cooler external temperature. Cooler temperatures create more potent, flavourful, and aromatic cannabis flower. Higher temperatures, especially those exceeding 82°F (28°C), can negatively impact your cannabis’ terpenes and the size of your buds.
Pay particularly close attention to temperature after week-6 and week-7, when terpenes are in their most important stage of development. High temperatures will burn away your plant’s terpenes.
Slightly lower your external temperature for the darkness phase of your plant’s light cycle. This mimics the naturally cooler temperatures of night time, and will maximize your flower’s terpene content. Terpenes play a major part in your flower’s aroma and taste, so more terpenes means richer flavours. Don’t let external temperatures drop below 59°C (15°C).
Optimizing your temperature during your plant’s darkness phase may also impact the colour of your plant, bringing out purples or blues on your plant’s flower and leaves (depending on the strain).back to menu ↑
Best temperature for drying and curing:
About 70°F (21°C) with 50% humidity for drying, and about 70°F (21°C) with 58%-65% humidity for curing.
Do not underestimate the importance of the drying and curing process. Curing cannabis is like aging wine. It can make the difference between mediocre and world-class cannabis flower.
The potency, look, flavour, smoothness, aroma, and effects of your cannabis flower will all be greatly shaped by the drying and curing process. The drying and curing process allows the chlorophyl in your flower to break down, creating a smoother smoke. Well dried and cured cannabis will also be less likely to pass on the unwanted potential effects of cannabis, like paranoia and anxiety.
Maintaining optimal temperatures throughout the drying and curing process will prevent the growth of mold, as well as over-drying your flower.
Want a second opinion on the best temperature for the flowering stage of your plant? Check out this great video by the Nug Doctor!
Want to learn more about the terpenes that exist in cannabis? Read our comprehensive guide to cannabis terpenes!