Long Day Photoperiodism

Long Day Photoperiodism refers to cannabis plants that require extended periods of continuous light exposure to trigger and maintain flowering. Unlike the more common short-day (long-night) photoperiodic varieties, long-day plants extend their vegetative phase under typical 12/12 light schedules and are often associated with equatorial or high-latitude geographic origins where daylight hours remain relatively constant year-round. This trait is comparatively rare in commercial cannabis breeding but appears in certain landrace populations and specialized breeding lines. Cultivators working with long-day photoperiodic material typically require extended light periods (16+ hours) or continuous light to induce reliable flowering, making them less practical for standard indoor operations.

Breeders studying long-day photoperiodism primarily focus on understanding genetic diversity and adaptation mechanisms within cannabis species. This family is valuable for lineage research, preservation of rare landrace genetics, and developing photoperiodic markers for breeding programs, though commercial application remains limited.