Cheerful, easy-to-grow, fast-growing, delicious, helpful — all these conditions apply to common sunflowers (Helianthus annuus). Wild forms grow throughout the United States, and many horticultural varieties exist for cut flowers, garden subjects, animal food, bird seed, oil, flour, and also for human food like snacks and in baked goods and cheeses. Sunflowers have inspired musicians; recall Vincent Van Gogh’s painting “Vase with Twelve Sunflowers.” English and Spanish common names of “sunflower” and “mirasol” document that the flowers turn throughout the afternoon to follow the course of sunlight.
Sunflowers are members of the aster family, with what looks like one big flower actually composed of numerous small tubular disc flowers that fill the central part and beam flowers, each with a showy elongate petal, ringing the disc. Flower heads range from the huge Russian Mammoth, 14 inches wide, to dwarf sunflowers with 4- to 5-inch blossom sizes. Originally sunflower cultivars had the most familiar sunny yellow ray flowers and tan to brownish disc flowers. Plant breeders today provide flowers where beam flowers are burgundy, terra cotta, bronze, red, or white, with many different disc flower colours. Some cultivars have bi-colored, striped or banded petals. Fluffy-headed double-flowered sunflowers such as “Teddy Bear,” “Lion’s Mane” and “Golden Pheasant” add interest to bouquets. Pollenless varieties were introduced in 1988 that make less messy floral arrangements.
Disc flowers, once pollinated by bees, begin to develop seeds. Oilseed cultivars with shiny, little black seeds yield sunflower oil and meal, and are also the most popular choice for birdseed. Russia is the leading producer of sunflower oil, with Russian sunflower varieties developed for premium seed oil material. Confectionery cultivars have bigger black-and-white striped seeds that are hulled, and the kernels are used for snacks and other food products. Sunflower meal makes a high-protein feed for livestock, and hulls provide filler in animal feeds and bedding.
Sunflower heights vary from 15 feet to dwarf plants 1 to 2 feet tall. Many commercial cultivars are single-headed, with just one bloom per plant. Wild sunflowers and lots of the cut flower and multi-colored garden cultivars are multi-branching, with many flowers per plant. Plants are very fast-growing. Sunflowers at a Kansas field grew 20 ins in seven days at the start of July. Plants are used for livestock fodder, for silage and plowed under as a green manure crop. Sunflowers are the only major crop that originated only in North America, most likely in the middle United States.
Sunflowers are annual plants that grow nearly anywhere. Seeds are sown after frost danger is over. Sunflowers are tolerant of most soils, but do best at well-draining, rich garden soil with organic substance additional. They need at least six hours of direct sunlight daily. Plant seeds at 4-inch-deep furrows, spacing them 6 inches apart and covering them with 1/2 inch of dirt. For big cultivars, thin plants to 1 1/2 to 2 feet apart and fill the furrow as seedlings develop to help support the tall stalk. Stake tall stems to support the heavy developing seedhead. Provide water during dry spells. Harvest seeds when the flower heads are dry, or leave seeds in place for birds to crop.