AbstractFive short‐season maize (Zea mays L.) hybrids were grown in 91‐cm and 46‐cm rows at populations of 48,000, 62,000 and 72,000 plants per hectare. The five hybrids responded similarly to changes in population density and distribution. All hybrids increased in grain yield with each increase in population and gave small but significant yield increases to narrowing the row width. Leaf area index (LAI) increased with increasing plant population or decreasing row width. The LAI values, even at the highest population, were much lower than those usually reported as giving maximum grain yield. This suggests that for short‐season hybrids the plant densities presently being used under standard production practices are too low to give maximum grain yields or to detect hybrid by population interactions for yield.