Sunflower
The sunflower (Helianthus annuus) is a plant that grows up to 3 meters (10 feet). Its large flower heads, which may be over 30 cm (1 foot) in diameter, are composed of many small individual flowers. The stem of the flower head is usually dark green and hairless. The leaves are stalked, and they may be over 30 centimeters (1 foot) long and 5 centimeters (2 inches) wide. The flower heads mature into large, brownish fruits.
Sunflowers grow best in full sun and light, loamy soil with moderate amounts of humus and a pH ranging from 6 to 7.5. They are not particular about the type of soil they grow in as long as it is fertile, well-drained, and not too high in lime. Sunflowers will grow on the poorest soils but will produce larger flowers if given good soil to start with. Sunflowers are available in cultivars that have single, semi-double, double, and fully double flowers. They come in a number of different sizes and habits, from short petite types less than 0.6 meters (2 feet) tall to giants more than 3.7 meters (12 feet) high with heads up to 20 centimeters (8 inches) in diameter.
Sunflowers need warm soil to sprout, but they do not tolerate hot weather after the flower heads have formed, and they should be harvested before the fall of frost if possible. In addition, sunflower seeds are subject to pre-harvest sprouting at high temperatures. The average yield from an area of sunflower cultivation is about 2 tonnes per acre, but the largest yields are obtained in areas with hot summers. Sunflowers are not difficult to grow. However, they are large plants with deep taproots that require deep soil with good drainage. They also need abundant water during their growing period and must be well fertilized. The soil should be well prepared before planting. In the spring, plants should be set out between March and May in full sun where they are to grow. A general-purpose fertilizer with a ratio of about 4:4:4 is added to the soil at a rate of about 150 pounds for each acre during preparation, and more may have to be applied as growth progresses.
The sunflower is an excellent source of edible vegetable oil, and each part of the plant is useful. The seeds are nutritious and yield around 25 percent protein on an analysis basis. They may be eaten raw or roasted, ground into a meal, pressed for oil or used in baking. The flowers also produce edible pollen that was traditionally gathered by Native Americans and later by others who believed it to have medicinal properties. The leaves are used as feed for animals, and the stems yield a strong fiber that is manufactured into ropes, brooms, mats, brushes, paper pulp, and cloth. The sunflower was an important food source to the Aztecs.
Production of Sunflowers is at 2 tonnes per acre, but the largest yields are obtained in areas with hot summers. Sunflowers need warm soil to sprout, but they do not tolerate hot weather after the flower heads have formed.