Iowa’s biggest cash crop got an early start this year. According to the U.S. Department of Agriculture, 57% of Iowa corn is already planted, that’s ahead of the 5 year planting average. That head start can mean a bigger crop come fall. Planting early doesn’t come without risks. Meaghan Anderson, Field Agronomist for the ISU Extension says The 24 to 36 hours after planting is a very important time because it takes in water at that point regardless of whether the soil temperature is warm enough for the plant to actually start growing.