How Early Is Too Early to Plant Corn?
Early planting is the buzzword this spring, but how early is too early to plant corn? When should you be planting?
Early planting is always the goal for corn production, but we rarely have a year like this one, where we have the opportunity to wait until we plant.
Research conducted by the University of Minnesota from 1988-2003 shows optimum planting dates of April 21 to May 6. Yields in years with planting dates earlier than April 18 only averaged 94% of the maximum.
Corn begins the germination process at 50 degrees F, but planting into cooler soils can still result in good emergence, if the weather and soils warm up after planting. Before you plant, pay attention to the upcoming week’s forecast. If the soil is 50 degrees F but the forecast predicts cold, wet weather, leave your planter in the shed.
A few years ago, we had a cool rain the first weekend in May, and it hurt germination in most of the heavy ground that was saturated. Imbibitional chilling injury occurs when the seed takes in (imbibes) cool water to start the germination process. The conditions in the first 24-48 hours after planting are the most critical.
Corn needs about 125 Growing Degree Days (GDDs) to emerge. This can occur in four days or can stretch out over three weeks. Ideally it will take 7-10 days, with all plants in the field emerging together. Cool weather will delay emergence, leading to uneven stands and the possibility of reduced yields.
This spring is looking a lot like the spring of 2012. That year I planted three times in April and three times in May, and did not see a significant advantage for the early April dates (April 4 and April 12). In 2012, we only gained 44 GDDs from April 6 to April 20, but gained 68 GDDs from April 21 to April 30, which illustrates the lack of advantage planting earlier than April 20. That spring, soils did not reach over 50 degrees F until April 22.
I recommend waiting until April 20 (at the earliest) to plant corn, depending on the three day forecast to follow. We all know what a 2” spring rain can do to our planting window. If the conditions are fit after April 20, plant corn!
