Night Temperature Effect

Night Temperature Effect refers to changes in terpene expression and phenotypic coloration that occur when cannabis plants experience cooler nighttime temperatures during flowering. Lower temperatures—typically 10-15°C below daytime conditions—can trigger anthocyanin production, leading to purple, blue, or red pigmentation in flowers and leaves. Breeders working in this category have documented that temperature fluctuations also influence terpene volatility and cannabinoid ratios, though mechanisms remain incompletely understood. This trait is particularly relevant in outdoor cultivation and controlled environment agriculture where diurnal temperature ranges are manipulated. Lineage records frequently report that certain genetic backgrounds express color changes more reliably under temperature stress than others.

Breeders selectively work with night temperature responsiveness to stabilize desired pigmentation traits and terpene profiles across generations. Understanding which parent lines reliably express these phenotypes under specific environmental conditions allows cultivators and seed producers to predict outcomes in different growing systems.