Taxonomically classified as Helianthus annuus, sunflowers that grow in the wild differ from those grown commercially, or by the home gardener, for the cultivation of their seeds. The domestically grown variety typically has a single stalk topped by a large flower composed of up to 2,000 individual seeds, which develop from individually pollinated flowers.
Wild sunflowers often produce multiple heads with much smaller flowers and usually do not reach the 5- to 7-foot height of the commercially grown varieties.
Vast fields of sunflowers can be seen in various parts of the country, where they turn their flowers to follow the sun throughout the course of the day in a process known as heliotropism.
Planting and Growing Sunflowers
The home gardener can easily grow sunflowers by planting seeds available at nursery stores or gardening centers. Choose a location where the plants receive the benefit of the full-day sun.
Sunflowers depend on a rich mixture of nitrogen in the soil. Select fertilizers high in nitrogen that also contain phosphorus and potassium. The plants will reach maturity in about 90-100 days from planting in most parts of the United States. They are ready to harvest when the black portion of the head turns to a deep brown color, typically in late September or October.
Although the flower seeds reach maturity earlier than these dates, allow the heads to dry out while still on the stalk to facilitate harvesting. The local bird and squirrel population also monitor this process closely and will quickly move in to feast on the seeds if the plants are not protected. Cover the entire head with an improvised cheesecloth bag or cut-up nylon stockings. Make certain that the covering permits adequate light and air to filter through. Plastic bags don't work, as they encourage rot-inducing moisture buildup and hold in too much heat.
Most commercial growers harvest sunflowers to extract their essential oils. Some of the commercially grown and nearly all of the homegrown product goes into using the seeds as food, either for the grower or for feeding birds, cattle or hamsters.
For human consumption, the seeds need to be extracted from the flower, dried to under 10 percent moisture content, roasted, salted and stored in containers. The requirements are the same whether it's for 10 sunflowers or 10 acres of them.
For home consumption, mix 1/4 cup of salt to a quart of warm water, add the seeds and soak overnight. Arrange them in single layer on a cookie sheet and roast them in a 200 degree Fahrenheit oven for three or four hours or until completely dry. Stir them occasionally. Store in tightly sealed glass jars. Nutritionally, a single serving--about 1/4 cup of unshelled nuts--has fewer than 200 calories and is high in polyunsaturated fat.