The flower head of a sunflower consists of between 1,000 and 2,000 individual flowers surrounded by large petals that are actually ray flowers that do not produce seed, according to Robert L. Myers and Harry C. Minor of the Department of Agronomy at the University of Missouri. Of all the seed crops in the world, the sunflower is the only domesticated plant from the U.S. grown for its food value. Sunflowers provide sunflower oil, birdseed and a snack food, but for many homeowners the sunflower is an ornamental plant to brighten the yard.
Till the soil to a depth of 8 to 10 inches in an area that receives at least six to eight hours of direct sunlight a day. Remove overturned sod, rocks and other debris and rake the area smooth.
Spread a 2- to 3-inch layer of compost or well-rotted manure over the area. Work the organic matter into the soil with a garden tiller or hand tools. Rake the area smooth for planting.
Plant sunflower seeds once the danger of frost has passed in your area to depth of ½ to 1 inch, depending on the size of the seed. Space seeds 8 to 10 inches apart. Water to moisten the soil to the seed depth and keep moist until seedlings emerge in five to 10 days.
Thin seedlings to 2 to 3 feet apart, when they are 3 to 4 inches high, for giant varieties and 1 foot apart for smaller varieties. Sunflowers can be planted closer to create a hedge, but bloom size will be reduced.
Water sunflowers deeply to saturate the soil to the root level once a week.