Gardeners first grew sunflowers over 3,000 years ago, according to Purdue University. Today, the flower's seeds are enjoyed as a tasty snack or element in many recipes. Instead of buying sunflower seeds in a store, plant and grow your own sunflower crop at home. Plant sunflower seeds as soon as the last frost date has passed in your region.
Choose a gardening site. Sunflowers thrive best in full sunshine and well-drained soil, according to Iowa State University.
Prepare the garden site by breaking up the soil to a depth of 6 inches with a spade, then mixing in 2 to 3 inches of compost. Follow with an application of an all-purpose granular fertilizer, like a 10-10-10 or 5-10-10 product, spread according to the rate listed on its label.
Plant the sunflower seeds 1 inch below the soil surface and space seeds apart by approximately 3 feet, according to the University of Minnesota. If you're growing more than one row of sunflowers, Purdue University recommends a row spacing of approximately 30 inches.
Water the planting site as necessary to keep the top 2 inches of dirt moist. The sunflower seeds will germinate within two weeks, according to Iowa State University. Once they're sprouted, reduce your watering to twice a week. Use enough water to wet the dirt to a depth of 6 inches.
Mulch around the sunflower plants with 2 to 3 inches of shredded leaves, wood chips or similar mulching material. This keeps weeds from competing with the sunflower plants for soil nutrients and water. Such weeds will reduce the health and seed output of your sunflowers, according to Purdue University.
Harvest the sunflower blossom approximately 100 days after sowing the seeds, according to Iowa State University. The head is ready for harvesting once its petals have wilted and fallen off and the back of the flower head is brown. Cut off the flower head and let it dry for two weeks, then rub your palm over the face of the flower to dislodge its seeds.