Short Day Cannabis

Short Day Cannabis refers to photoperiod-sensitive cultivars that initiate flowering when day length drops below a critical threshold, typically 12-14 hours of light. This classification encompasses both traditional landrace and modern breeding lines selected for rapid transition to reproductive phase under natural or controlled light cycles. Short Day varieties are distinct from autoflowering genetics, which flower based on age rather than light duration. Lineage records frequently report Short Day traits in equatorial and subtropical landraces, where consistent day length historically triggered seasonal reproduction. Understanding photoperiod response remains foundational to indoor breeding programs, outdoor cultivation timing, and preservation of wild or heritage germplasm.

Breeders working with Short Day genetics leverage predictable flowering windows for multi-crop annual production and synchronization of male and female flowering for controlled crosses. This trait enables rapid cycling in controlled environments and helps maintain genetic stability in breeding populations where light schedules are standardized.