Growing Degree Days (GDD)
Accumulate growing degree days from daily maximum and minimum temperatures to time planting, pests and crop stages, free online.
About this calculator
GDD = max(0, (T_max + T_min) ÷ 2 − T_base), with T_max capped at an upper threshold (30 °C for corn) and T_min floored at the base. Common bases: 10 °C (50 °F) for corn, 5 °C for wheat and cool-season crops. Crops and insects need a set number of accumulated GDD to reach each stage.