What Causes Early Seed Pods on Sunflowers?

Growth Process

• Sunflower plants come to maturity and seed pod harvest 85 to 95 days after planting, with variations according to cultivar. Sunflower seed pods develop at predictable growth intervals. The development of sunflower seed pods is related to water availability. They are most sensitive to water stress just before flowering through seed pod growth. Sunflower plants germinate approximately 11 days after planting, when temperatures are at least 46 to 50 degrees Fahrenheit.

Young Plants

• A sunflower's first leaves are known as cotyledons. They are bright green and two to three times longer than wide. The plant's center stalk develops side branches on many species of sunflower. They begin to grow a vigorous taproot and extensive surface root system. Their stems are round shaped in early development and become angular and woody as the plant matures. Sunflowers are photo-tropic, turning their leaves and flowers towards the sun's path through the sky. This capability is thought to increase their light interception and photosynthesis.

Cultural Requirements

• Lack of adequate water may cause seed pods to develop late or under develop. Sunflowers use 16 to 22 inches of water during their growth from young plant to maturity. The flower head appears in 33 days after plant emergence and mature seed pods are ready for harvest in approximately 65 days. Small sunflowers produce about 800 seeds and large flowers may contain over 2,000 seeds.

Pollination

• Bees carry pollen from plant to plant to create fertile seed pod development. Native bee species are more effective pollinators than domesticated honeybees, according to the United States Department of Agricultural Research Service. The sunflower leafcutting bee (Megachile pugnata) species is native to southern Canada and all the United States except the lower Mississippi Valley and the Gulf Coast. Some sunflower cultivars produce heavier seed pod flower heads when pollinated by the sunflower leafcutting bee.