What are ideal temperatures for marijuana plants that are flowering and/or in vegetative growth?
For the most part, the best growth rates are going to come when the temperature ranges from 70 to 74*F during the light period, with a drop of around 10 degrees (to no lower than the high 50’s) during the dark period. Photosynthesis slows down significantly if the temperatures are lower during the light period. A temperature rise correlates to stable photosynthesis rates, but increased metabolic rates—an action that causes the marijuana plant to use much of the sugar produced during photosynthesis.
When CO2 enrichment is used and light intensity is optimized, the marijuana plants perform better at higher temperatures during the day (mid-80s F) and during the dark period (mid-70s F). The higher temperature is frequently useful for cannabis growers, since the heat from lights and other equipment must be managed.