What conditions do sunflowers live in?

Sunflowers are prairie natives, which means that they need lots and lots of sunlight and wide open spaces. The plants can grow to 12 feet in height, and stalks placed too closely can suffer from reduced airflow, in the form of mildew. That being said, be aware that the heavy flower heads can pull the plants right over in windy conditions. The multi-branched varieties suffer less from this problem. Ordinary garden soil works best, as rich soil will produce more leaves than blossom.