Seed companies often characterize hybrids as fixed-ear or flex-ear types. Hybrid descriptions indicate that ears of fixed-ear hybrids do not adjust as readily to environmental conditions, but ears of flex-ear hybrids do. Flex-ear hybrids are often targeted for more difficult growing conditions and are planted with fewer plants per acre compared to a fixed-ear hybrid. The objective of these studies was to determine if hybrids characterized as flex-ear or fixed-ear have different optimum plant densities in different environments. Two hybrids (one characterized as fixed-ear, one characterized as flex-ear) were planted at several locations in Kansas in several different years. At each location, plant density was established by thinning before V5. In only a few instances did response to plant density depend on hybrid type. In most environments, yield response to plant density was similar for both fixed and flex-ear hybrids.