Growing Degree Days for Fresh Market Sweet Corn Varieties

Emmalea Ernest, Scientist – Vegetable Crops; emmalea@udel.edu

Growing degree day (GDD) calculations can be used to schedule sweet corn plantings so that a continuous supply is available during the harvesting and marketing season. The method for doing this is described in a past Weekly Crop Update article: Using Growing Degree Days to Schedule Sweet Corn.

When scheduling sweet corn plantings and choosing varieties, it can be useful to know the typical number of GDDs from planting to harvest for a particular variety. I conducted sweet corn trials in 2019 with the following planting dates: April 17, May 21 and June 20. Days to harvest and GDDs to harvest from those trials are reported in the table below.

Daily growing degree days were calculated using the following formula:

Daily GDD = (Daily Max Temp + Daily Min Temp)/2 – 50

When the Daily Max Temp exceeded 86°F, 86 was used as the daily max temperature.

Accumulated GDDs were calculated by adding daily GDDs from the day after planting until the day before harvest.

Average, Maximum and Minimum Days to Harvest and Growing Degree Days to Harvest for Sweet Corn Varieties in 2019 Sweet Corn Trials in Georgetown, DE

Days to harvest and GDDs to harvest varied by planting date but some varieties had more consistent time and GDDs to harvest. In the charts below note that the varieties Flagler, XTH 3174 and Mattapoisette had very predictable maturity based on GDD, whereas Sweet Ice, Mirage, and Xtra Tender 278A had more variable accumulated GDDs between planting and harvest.

Growing degree days for bicolor supersweet varieties trialed in 2019. Box extends from maximum to minimum values, x indicates average GDD, line indicates median GDD.

Growing degree days for white supersweet and se varieties trialed in 2019. Box extends from maximum to minimum values, x indicates average GDD, line indicates median GDD.