790 Helianthus annuusCommon Names: common sunflower, sunflower, mirasol Family: Asteraceae (aster/daisy Family)
Are they called sunflowers because the flowerhead looks like the sun or because it follows the sun across the sky, looking east in the morning and ending the day facing the setting sun in the west?
There are so many different-looking cultivars of sunflower that it's hard to make generalizations about the whole species. Most sunflowers are tall 8-15 ft (2.4-4.6 m); most have rough-hairy oval to heart shaped leaves; most have large flowerheads 8-12 in (20-30.5 cm) across; and most have yellow ray florets and purplish brown disk florets. The ray florets of sunflowers are sterile, and only the disk florets produce seeds. All the sunflower cultivars are fast-growing annuals, and many are rather rank coarse-textured plants. 'Autumn Beauty' is smaller, to 5 ft (1.5 m), with flowerheads to 6 in (15 cm) across and rays that can be mahogany, sulfur yellow, bronze or brownish red. 'Teddy Bear' is even smaller, to 3 ft (0.9 m), with bright yellow chrysanthemum-like double flowerheads to 5 in (12.7 cm) across. 'Russian Giant' gets over 12 ft (3.7 m) tall and has bright yellow flowerheads a 1 ft ( 0.3 m) across and it's often grown for its edible seeds. 'Holiday' is branched with many 4-5 in (10-12.7 cm) yellow flowerheads. 'Italian White' has 4 in (10 cm) flowerheads with white rays and black disk florets. 'Velvet Queen' has 5 in (12.7 cm) burgundy and maroon flowerheads. 'Sunspot' is only 2 ft (0.6 m) tall but has full-sized 10 in (25 cm) flowerheads. Sunflowers grown commercially for the oil that is pressed from the seeds include 'Peredovik', 'Progress' and 'Rostov'.
The wild sunflower, Helianthus annuus, from which all the cultivars have been derived grows naturally in almost all of North America from central Canada to northern Mexico. It grows in prairies and dry, open areas, and is sometimes a weed in cultivated fields and pastures. Sunflowers are widely grown commercially for the oil that is extracted from the seeds. Russia is the world's largest producer, Argentina is second and the U.S. is third. Most production in North America is in the northern Great Plains, especially Minnesota, the Dakotas and Manitoba.
CultureSunflowers are easy to grow in any well-drained, neutral to slightly alkaline soil. Add lime if your soil is acidic. Fertilize the bed with rotted manure or a balanced chemical fertilizer for maximum growth. The taller cultivars may fall over if not given support. Light: True to their name, sunflowers prefer full sun. They are likely to stretch for the sun and fall over from their own weight if grown in partial shade. Moisture: Water your sunflowers freely for maximum growth, but they can survive periods of drought. Hardiness: USDA Zones 4 - 11. Common sunflower is a warm season annual and some of the cultivars can complete their life cycles in as little as 60 days. Sunflowers are noted for their tolerance to heat and dry conditions. They perish after the first frost, though. Propagation: Sow sunflower seeds in place after the last frost, or give them a head start indoors a few weeks before setting out. Little seedlings transplant easily. The seeds you gather yourself from some of the cultivars may not come true, so you should purchase sunflower seeds.
The larger sunflowers can be a little too rangy and coarse for smaller gardens. They often are relegated to the back fence or used as temporary screens. Grow the biggies in the wildlife garden or behind the vegetable garden. Many of the small cultivars are good in masses in the flower bed or in the annual border with other bright colored flowers. Dwarf cultivars such as 'Teddy Bear' are good in containers. Fast growing sunflowers, especially the really big cultivars, are favorites with children. Kids are fascinated with the large size and bright colors of this easy-to-grow garden giant. They love the way it follows the sun. Bees and butterflies frequent the flowers, and all sunflowers are good and long lasting as cut flowers. Birds (especially finches and cardinals) and squirrels will help themselves to the seeds. Some people grow sunflowers just for the seeds which they harvest for themselves or to feed the birds in the winter. If you want to harvest sunflower seeds, cut the flowerhead off when the back is brown and no trace of green remains. Hang upside down in a warm, dry, well ventilated place and scrape the seeds off when the back of the flowerhead is papery dry. Roast or eat raw.
Sunflowers are supposedly allelopathic: their roots give off a chemical that inhibits the growth of other, nearby plants. Most gardeners don't seem to notice this, though.
Kansas' State Flower produces the world's second most important and valuable oil seed. (Coconut oil comes first.) The seeds contain 35-40% oil. They are high in polyunsaturated fat and contain no cholesterol. The seeds are a good source of protein, starch and (especially) calories. American Indians were quite dependent on sunflowers; they made flour for cakes and bread, and oil for cooking and hair dressing from the seeds. If you're buying sunflower seeds for feeding the birds, always get the more nutritious black-oil sunflower seeds, not the striped ones. The cardinals, towhees, tufted titmice, chickadees, blue jays, and red-bellied woodpeckers in my North Florida yard go through about 20 lbs (9 kg) of sunflower seeds each month!
There are some 70-80 species of Helianthus, all native to the New World. Some are perennials, many are popular garden ornamentals, and one, Jerusalem artichoke (H. tuberosus), is grown throughout the world for its edible tubers. Beach sunflower (H. debilis) is used as a border plant and groundcover in southern seaside gardens. There are several sunflower hybrids in cultivation, too.
Some individuals are allergic to sunflower foliage and may develop a skin rash from contact.
Steve Christman 09/04/00; updated 06/23/01, 05/29/03, 09/10/03, 6/26/04