The Growth Process of a Sunflower

Germination

• Sunflowers are not demanding in their preferences for soil type and planting location. They can grow in either sandy or clay soils, and their nutrient demands are not as high as some other agricultural plants. Young seedlings have some resistance to frost, so seeds can be sown as early as mid-March in the southern United States. In the northern United States, a mid-May planting date is safer. The average time from planting to seedling emergence is approximately 11 days.

Growth

• The sunflower seedling develops a deep tap root and dense system of surface roots, and its vertical stem grows quickly. In most cultivars, the stem does not branch. In young plants, the stem is green and round, but it becomes woody with an angled cross-section as the plant matures. Like the flower head will later, the leaves of the sunflower follow the angle of the sun during the day, turning themselves in order to catch as much sunlight as possible. In general, the time between the seedling's emergence and the beginning of the flower head development is approximately 33 days.

Flowering

• The flower head of a sunflower is not a single flower as it appears to be, but rather a complex cluster of 1,000 to 2,000 small individual flowers of two different types. The flowers around the outside of the head are ray flowers from which emerge the petal-like structures that form the "flower" with which we are familiar. The flowers in the center of the head are known as disk flowers. These flowers have reproductive organs, unlike the ray flowers, and they produce pollen and develop into seeds.

Seed Development

• Approximately 30 days after flowering, the sunflower will produce mature seed. Each of the disk flowers in the flower head is capable of producing a seed. These seeds are used commercially for oil production, livestock feed, bird seed and human consumption. Those seeds not harvested or eaten by wildlife may fall to the ground and germinate the following growing season.