Brazil has two growing seasons for maize (Zea mays L.) production: summer and winter. The additional maize produced in the winter and the high-yielding opportunities in the summer season make it important to understand responses of maize hybrids to row spacing and plant population across the two annual Brazilian growing seasons. In the 2015 to 2016 summer season and the 2016 winter season, maize response to plant population, ranging from 60,000 to 90,000 plants ha -1 , was evaluated for three hybrids in 0.45-, 0.60-, 0.75-, and 0.90-m row spacing. Plant architecture traits, grain yield and yield components did not differ with row spacing, and their responses to plant population were not affected by hybrid type and/or row spacing. The DKB390PRO2 hybrid (single cross) demonstrated better grain yield performance in the summer, whereas the BG7049YH hybrid (three-way cross) had the highest yield in the winter. Plant and ear height increased linearly in response to plant population in the summer season, whereas other plant architecture traits, ear leaf chlorophyll concentration, and grain yield components decreased linearly with increasing plant populations in both seasons. There was a quadratic response in maize grain yield to plant population, and it was maximized with 78,688 plants ha -1 in the summer, and 71,206 plants ha -1 in the winter. Our results show preliminary evidence that regardless of row spacing, maize grain yield can be maximized with DKB390 hybrid (single cross) with 78,500 plants ha -1 in the summer, and BG7049YH hybrid (three-way) with 71,000 plants ha -1 in the winter season.