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Agronomic Crops Network

Ohio State University Extension


ANR Factsheet for tracking Growing Degree Days in Corn

Corn Ear

Because of differences in the growing season for corn across Ohio, practitioners need a method of accurately rating crop’s maturity to inform crop management decisions for adequate yield, quality, and grain moisture at harvest. For this reason, we rate hybrid maturity based on “Growing Degree Days” (GDD), or heat units. Because a corn hybrid requires a specific number of GDD to reach maturity—a number that is independent of the crop’s total number of growing calendar days—the GDD method is accurate and should be considered by today’s practitioners.

Corn Growth Stages

Figure 1. Corn at vegetative and reproductive phases during the growing season.

A step-by-step guide is available with guidance on how to estimate corn GDD, the GDD requirement for vegetative and reproductive stages, as well as available resources that can assist in this process.

Corn Growing Degree Days:
A Method of Maturity Rating for Hybrids
Access AGF-101 here:  

The GDD system has important applications for tracking crop progress and decision-making on the farm to achieve high corn productivity and profitability.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.