QUESTION: TO PLANT OR NOT TO PLANT? For farmers who are waiting to plant, waiting for the opportunity to get into the field as soon as soil conditions are favorable and weather warms, those farmers are looking at the calendar. Is it still more important, at least at this time in early May that you plant into ideal soil conditions as opposed to what date it is?
"Yes," says Holmes. Long-term ISU research trials show the ideal time is April 15 to May 2 for planting corn in central and northwest Iowa. It's April 11 to May 13 in southern Iowa, and April 12 to May 2 in northeast Iowa. That's to reach 100% of yield potential. But May 13 is 99% here in central Iowa, "so I tell farmers to wait. They're better off planting when weather and soil conditions are more favorable."
Although corn kernels absorb soil moisture when soil temperatures are less than 50 degrees F, they won't begin germination until soil temperatures reach almost 50 degrees F or higher. ISU Extension corn agronomist Roger Elmore offers this guideline to help you make a decision: "If the sun is shining and calendar date for your part of Iowa is on the early side of the range listed above, and if soil temperatures are in the high 40s or higher and climbing, you should look at the five- to seven-day weather forecast. Plant corn if the forecast calls for more of the same. If, on the other hand, the five to seven day forecast calls for a good chance of cold, wet weather settling back in for a while, keep the seed in the bag."