Critical Dark Period
Critical Dark Period refers to the minimum uninterrupted darkness required for cannabis plants to initiate and maintain flowering. Most photoperiod-dependent cultivars require 12 continuous hours of darkness to reliably transition from vegetative growth. Breeders and researchers use this classification to understand strain-specific timing variations and light-cycle sensitivity. Some cultivars show flexibility within a 10–14 hour range, while others demonstrate strict requirements. This trait has breeding relevance for indoor cultivation optimization and for developing strains suited to varying latitude conditions. Critical Dark Period data helps growers and breeders predict flowering onset and duration.
Critical Dark Period strains
No strains tagged into Critical Dark Period yet — they'll appear here as breeders submit lineage records under this classification.
Critical Dark Period refers to the minimum uninterrupted darkness required for cannabis plants to initiate and maintain flowering. Most photoperiod-dependent cultivars require 12 continuous hours of darkness to reliably transition from vegetative growth. Breeders and researchers use this classification to understand strain-specific timing variations and light-cycle sensitivity. Some cultivars show flexibility within a 10–14 hour range, while others demonstrate strict requirements. This trait has breeding relevance for indoor cultivation optimization and for developing strains suited to varying latitude conditions. Critical Dark Period data helps growers and breeders predict flowering onset and duration.
Breeders working with photoperiod genetics track Critical Dark Period thresholds to develop cultivars with predictable flowering windows for specific growing environments. Strains with flexible dark-period requirements are often selected for cultivation in regions with variable seasonal light cycles.
Educational reference · Cultivar metadata only · No medical claims