Enter your Maximum Temperature, Minimum Temperature, Base Temperature, Number of Days, and Comparative Relative Maturity (CRM) into the GDU Calculator to find your crop's Total Growing Degree Units, Average Daily GDU, and how far along your corn is toward Silking and Maturity.
Total Growing Degree Units
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Average Daily GDU
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Progress to Silking
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Progress to Maturity
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Growing Degree Units (GDU), also known as Growing Degree Days (GDD), are a measure of heat accumulation used to predict crop growth stages. GDUs quantify the amount of heat available over a growing season, helping optimize planting schedules and harvest planning.
GDU is calculated using the formula: GDU = (Maximum Temperature + Minimum Temperature) ÷ 2 - Base Temperature. For corn, the base temperature is typically 50°F. Any negative values are set to zero.
Corn typically needs 90-120 GDUs to emerge from planting, depending on soil conditions and planting depth. Full emergence usually occurs within 100-150 GDUs under normal conditions.
Base temperature is the minimum temperature below which plant growth stops. For corn, it's 50°F. Cool season crops like wheat use 40°F, while warm season crops may use 60°F as their base temperature.
GDUs help determine optimal planting times by tracking accumulated heat units. Farmers can use historical GDU data to predict when soil conditions will be suitable and when crops will reach critical growth stages.
GDU calculations require local temperature data. You can obtain this from weather stations, agricultural extension services, or online weather databases. Many agricultural websites provide location-specific GDU tracking tools.
Comparative Relative Maturity (CRM) is a rating system that indicates how many GDUs a corn hybrid needs to reach physiological maturity. Higher CRM numbers indicate longer-season hybrids that require more heat units.