September and October is an excellent time to plant the sunflower. You can plant them this time of year for a beautiful fall bouquet.
You might have noticed that sunflowers are not usually sold as transplants. This is because sunflowers are fairly difficult to transfer from pot to garden.
This leads to the survivability and establishment rate to become very low.
This means you'll need to purchase sunflower seeds to direct seed right into the garden where you want these plants to grow and thrive.