Growing degree-day
HEURISTIC TOOL IN PHENOLOGY
Growing degree day; Growing degree unit; Growing degrees; Growing-degree day; Growing point
Growing degree days (GDD), also called growing degree units (GDUs), are a heuristic tool in phenology. GDD are a measure of heat accumulation used by horticulturists, gardeners, and farmers to predict plant and animal development rates such as the date that a flower will bloom, an insect will emerge from dormancy, or a crop will reach maturity.