Photoperiod Long Day

Photoperiod Long Day plants are cultivars that require extended daily light exposure to initiate and complete flowering, typically necessitating 14+ hours of light per day. This classification encompasses cannabis strains bred or selected to respond to lengthening daylight cycles, making them well-suited to outdoor cultivation in northern latitudes or controlled environments with manipulated lighting schedules. Unlike autoflowering varieties, Long Day photoperiod plants remain in vegetative growth until light duration shifts, allowing extended development periods. This trait is common in landrace and heirloom genetics from regions with pronounced seasonal variation. Breeders working in this category often prioritize yield potential and cannabinoid expression during extended growing seasons.

Long Day genetics enable cultivation strategies that maximize vegetative biomass accumulation before flowering, making them valuable for breeding programs targeting larger plant structure or complex trait stacking. Photoperiod sensitivity remains a core selection criterion in outdoor breeding lines adapted to temperate and subarctic growing zones.