Long Day Photoperiod

Long Day Photoperiod plants are cannabis cultivars selected or bred to respond to extended light cycles, typically requiring 14+ hours of daily light to initiate and complete flowering. Unlike autoflowers or strict short-day varieties, these plants remain in vegetative growth under longer photoperiods and transition to reproductive phases when day length shortens below a critical threshold—often around 12–13 hours. This family is commonly associated with outdoor cultivation in northern latitudes where summer days are extended, as well as indoor operations using extended light schedules to maximize vegetative development before controlled flowering. Breeders working in this category often incorporate genetics from high-latitude landrace populations or select parent plants demonstrating photoperiod sensitivity. Understanding photoperiod dependency is essential for timing planting, managing

Breeders leverage long-day photoperiod traits to extend vegetative growth periods, allowing for larger plant biomass and more branching before reproduction. This trait is valuable for cultivators seeking longer productive seasons in temperate and boreal regions, and for indoor growers who want precise control over growth and flowering timing.