Choose an area that offers loose soil, at least six hours of direct sunlight and protection from the wind. Till the soil 2 feet down and 3 feet wide to create a well-draining bed for the sunflower's long roots. Add fertilizer to the bed just before planting.
Plant the seeds after the last frost date. The ideal soil temperature is between 55 to 60 F. Place each seed 1 inch deep, and space the seeds 6 inches apart. Plant more seeds every couple of weeks for regular blooms throughout the summer. At the time of planting, add a bamboo stake or other support near the seed. Secure the sunflower to the support as it grows to keep the heavy flower heads from drooping.
When the seedlings emerge, water a circle around them. Water 4 inches away from the seedlings to hydrate the spreading roots. When the sunflower is stronger, provide several gallons of water per week to encourage the roots to grow deeply.