Sunflowers are a large flower that can grow to up to a meter in height and produces one large flower. However, when looking closely at this large flower it is visible that the head of the plant is composed of many flowers clustered together. The outer flowers are called florets and look like petals which are commonly yellow in color but can be orange, maroon, and various other shades. The inner flowers make up the central disk and are responsible for seed production.
Growing Requirements for Sunflowers
Sunflower plants are very picky about soil quality. They require moist soils that have good drainage and fertilizers. The soil cannot be too high in nitrogen and must have potassium and phosphorus present. The best way to make sure soil nutrient levels are correct is to perform soil tests.
The seeds should be planted in damp soil about one to two inches deep and twelve inches apart. If the gardener prefers sunflowers with large heads the seeds should be placed even further apart to allow for the roots to expand further than they would otherwise. Shoots will appear nearly two weeks after being planted and are full grown within ninety days. The seeds should be planted in late spring to early summer in order for the plant to have a maximum amount of sunlight in the summer.
Taking Care of Sunflowers
Sunflowers need full sunlight. They actually have a curious habit of rotating their heads in order to face the morning sun in the East. The flowers can be sensitive to overcrowding and thus new seedlings should be removed. Dead foliage and leaf litter should also be removed, as well as weeds in order to ensure maximum growth. Also, larger sunflowers should be staked in order to prevent bending and falling when exposed to wind and rain.
History and Uses of Sunflowers
Sunflowers have been a domestic crop for upwards of a thousand years. There are about 67 species of sunflowers and it is believed that they are native to both North and South America. Today, sunflowers are distributed worldwide and are one of the most proliferate crops in mid-west America.
Sunflower oil and seeds are common foodstuffs that come from the flower. The seeds can be used intact or they can have their oil extracted to use in cooking. Sunflower seed oil is one of the most preferred oils due to its light color, high level of unsaturated fats, and bland flavor. In fact, sunflower seed oil accounts for about 14 percent of the world’s oil.
The most common sunflower disease is sclerotinia which in a fungal disease that rots the plant. Caused by airborne spores, the disease starts in the root and works its way upwards. The disease produces a distinctive white mold that also affects many other plants, such as soybeans.
Additional Information on Sunflowers
Additional information about how to grow sunflowers can be found on these websites:
General and health information can be found at the National Sunflower Association.
University of Georgia Extension covers Growing Sunflowers in the Home Garden