Growing Degree Days
Growing Degree Days (GDD) is a heat accumulation metric used to predict cannabis development timing based on temperature. Calculated by summing daily temperature averages above a crop-specific baseline (commonly 50°F/10°C), GDD helps breeders and cultivators estimate when photoperiod-sensitive and autoflowering varieties reach key lifecycle milestones—germination, vegetative transitions, and flowering completion. Different strain families and regional landraces show distinct GDD requirements; equatorial and tropical genetics often require fewer accumulated heat units than temperate-origin lines. This classification is particularly relevant for outdoor and greenhouse cultivation planning, where environmental heat accumulation directly influences phenotype expression and harvest timing.
Growing Degree Days strains
No strains tagged into Growing Degree Days yet — they'll appear here as breeders submit lineage records under this classification.
Growing Degree Days (GDD) is a heat accumulation metric used to predict cannabis development timing based on temperature. Calculated by summing daily temperature averages above a crop-specific baseline (commonly 50°F/10°C), GDD helps breeders and cultivators estimate when photoperiod-sensitive and autoflowering varieties reach key lifecycle milestones—germination, vegetative transitions, and flowering completion. Different strain families and regional landraces show distinct GDD requirements; equatorial and tropical genetics often require fewer accumulated heat units than temperate-origin lines. This classification is particularly relevant for outdoor and greenhouse cultivation planning, where environmental heat accumulation directly influences phenotype expression and harvest timing.
Breeders document GDD thresholds when characterizing new lines, especially when adapting genetics to different climates or creating regionally-suited cultivars. Selecting parent plants with known GDD profiles enables predictable crop planning and helps identify which crosses maintain stability across varied growing seasons.
Educational reference · Cultivar metadata only · No medical claims