Corn in Mississippi
When is the optimum time to plant corn?
The standard guideline for determining earliest planting date is when morning soil temperature at a 2 inch soil depth is 55º F or 50º F at a 6 inch soil depth. Planting before the soil temperature is warm enough for germination greatly increases the potential for stand failure.
Soil temperature may vary depending upon soil texture, slope, color and amount and type of crop residue. Thus, randomly measuring soil temperature with a thermometer within a field should provide a reliable indicator of desirable conditions for stand establishment.
Corn produces highest yields when planted within 4 - 5 weeks after soil temperature is warm enough for germination. This has historically corresponded with the following calendar dates:
Geographical Region of Mississippi:
Coastal : February 25 - March 15
Southern: March 5 - April 10
Central: March 15 - April 20
Northern: March 20 - April 25
Although early planting is a critical component of successful corn production, planting corn extremely early (substantially before suggested dates), even if soil temperatures are warm, provides little if any agronomic benefit, while increasing risk of stand failure. Although the growing point of a corn plant remains underground until about the V6 growth stage (12" tall), temperatures cold enough to freeze the soil can kill seedlings. Falling soil temperature also substantially increases the likelihood of stand failure, since seedling vigor is closely correlated to soil temperature. Extraordinarily early planting enhances maturity very little, because corn growth rate is correlated to temperature, and heat unit accumulation (GDD 50) is historically very low during early March. See Mississippi historical freeze dates and soil temperatures.