Plant sunflower seeds directly into the soil after the last frost date in your region. Sow the seeds about 1 to 2 inches deep and space them according to the specific variety's recommendations—typically around 6 to 24 inches apart depending on the sunflower type.Sunflowers thrive in full sun so select a spot with at least 6 to 8 hours of direct sunlight per day. Ensure the soil is well-draining loamy and enriched with organic matter.Sunflowers typically bloom in mid to late summer. Once the flower heads mature and the back of the flower turns yellow the seeds are ready for harvest. You can cut the flower head and hang it upside down to dry. Extract the seeds by rubbing or brushing them off the head.