After calculations, there has been 205 cumulative GDUs from planting starting April 19 through May 19. Temperature data for this calculation was taken from AccuWeather for Primghar, Iowa.
- GDUs stand for “Growing Degree Units,” which are a measurement of the amount of heat needed for a corn plant to reach various developmental stages, such as tassel or maturity. Each hybrid has its own unique GDU number, which can typically be found on the seed bag tags.
- To calculate, use the following equation: GDU = (Daily High Temperature + Daily Low Temperature)/2 – 50
- If the high temperature is above 86, still use 86. Do not use a number greater than 86. If the low temperature is below 50, still use 50. Do not use a number lower than 50.
- Start calculating GDUs the day corn is planted. Then add up the GDUs each day to keep track of your cumulative GDUs.