Although harvest time is dependent on the growing zone, many corn harvests in the United States take place in mid September and October. In Iowa, a state known for its corn production, during slow harvests when corn is late to mature, harvesting may be pushed back as late as November, states Iowa Corn.
Farmers plant corn whenever the soil becomes warm enough to facilitate the germination of seeds. In some places in the United States, this is as early as April, but planting season in some states may be pushed back until May.
In the case of field corn, which is dried and stored, farmers sometimes delay harvests even longer to make sure the corn is fully dried out, notes Iowa Corn. This allows for a longer storage period.