We grow sunflowers every year in our back yard.
Last year we grew one sunflower that was 10 feet 8 inches high. Sunflower seeds from this plant usually grow two types of sunflower plants. We have seen 6 foot plants and the giant 10 foot plus sunflower plants.
These grow anywhere in the US.
Seed packets come with 20 seeds and grow easily.
Pictures of sunflower seeds below.