For Winter Wheat, the timing of growth stage progressions through the season is dependent on both the variety and environmental cues such as day length, or temperature. The Karow Winter Wheat growing degree day model uses heat units and time as a method to estimate plant phenological stages through the growing season. This can be helpful as a crop management tool, or to predict development of leaves and tillers.

Calculating Growing Degree Days

For this model, a lower temperature threshold of 32F is used to calculate growing degree day accumulation beginning at the time of planting. Growing degree days can be calculated from daily high and low temperatures, or via the Pest Prophet app, which uses hourly temperature data for a given field. This can be used to predict development of different leaves and tillers.

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Karow et al. Winter Wheat growing degree day model. 1993