Don't plant all your seeds at once in May. Drop a few seeds every two weeks until mid-July to ensure a continuous "wave" of yellow through October.
Sunflowers are generally classified as summer annuals, but their blooming window is surprisingly wide. Most varieties take between to reach maturity. This means that if they are planted in mid-to-late summer, their peak performance naturally aligns with September and October. do sunflowers bloom in the fall