Soybean yields often increase, up to a point, with increasing plant population. However, soybean yield responses to plant population are generally small and often inconsistent. In general, when plant populations are increased, plant height increases, and there are greater yield losses from lodging. Soybean seed prices have increased tremendously over the last couple of years. Our hypothesis is that we can reduce our seeding rate cost if we need to replant a field because later in the season soils are warmer and seedling mortality lower. The objective of this experiment was to determine the optimum plant population across different planting dates in northeast Iowa.