Why Temperature Matters

Why Is Temperature Important When Growing Cannabis?

Can cannabis stand freezing temps? What happens if your grow room gets too hot?

Different afflictions can happen from high or low temps, so let me break that down for you.

Learn more details below….

Too Low (Cold) Temps

Colder temps will tend to slow down growth. Temps lower than 60°F (15°C) tend to upset plant growth and freezing temperatures will shock or even kill a cannabis plant.

Plants are more susceptible to certain types of mold when it’s cool, especially if it’s also damp. Colder temps and big temperature fluctuations contribute to over-purpling of leaves and can also reduce photosynthesis.

A plant that is grown in relatively cold temps can survive, but it will never grow as fast or as well as a plant that is given proper temps. Indoor plants tend to be much more susceptible to cold than outdoor grown plants.

Too High (Hot) Temps

While cannabis plants don’t usually die from the heat, too hot temps will cause plants to grow much more slowly.

Please note temps above 80°F (26°C) in the flowering stage will not only slow down bud growth, but can reduce the potency and smell of your buds – keeping the grow room temperature under control is especially important in the flowering/budding stage!

In the heat, cannabis is also more susceptible to many problems, including spider mites, white powdery mildew (especially if it gets humid, too), root rot, nutrient burn (from increased water transpiration), increased stretching, wilting due to root oxygen deprivation, and reduced “smelliness” of buds (as terpenes can burn away at higher temps).

More About the Upper Limits of Temperature

  • With bright grow lights (such as 600W HPS and brighter), cannabis plants of all stages can thrive at slightly higher temps up to a max of about 85°F (30°C) even with no CO2 enrichment, as long as there is low relative humidity and plenty of air movement.

  • Cannabis plants can thrive at even higher temperatures, up to an ultimate max of about 95°F (35°C), in an environment with low humidity, extremely bright grow lights and enriched CO2 (above 1500 PPM) – this is not your average grow