Will a Freeze Affect My Sunflower Seeds If Not Harvested?

Description

• The sunflower is an annual plant native to North America. The plant's head consists of 1,000 to 2,000 individual flowers joined at one base, rather than a single flower. The leaves grow towards the sun's rays, which increases photosynthesis. Different varieties range in height from 3 to 4 feet for dwarf cultivars and up to 7 feet for field-crop varieties.

Growth Requirements

• Sunflowers grow from planting to maturity in about 100 days in temperate climates. Spring is the best seed-planting time. The plants receive springtime rain, which is essential for growth and germination during warm the summer months for mid- to late-summer yields. The flower grows in most soils that drain well and with proper nutrient-rich fertilizers. Nitrogen is an important nutrient to grow sunflowers with reasonable oil and seed production.

Climate

• Sunflowers tolerate temperature ranges. Freezing temperatures do not affect early seedlings, but maturing seeds do not respond well to freezing temperatures. In Northern climates experiencing cold winters, sowing seeds too early affects the plant if a late frost occurs before it reaches its six-leaf development stage. While the seeds germinate with temperatures as low as 39 degrees F, satisfactory seed production results in temperatures ranging from 46 to 50 degrees F with optimal production results in temperatures between 70 and 78 degrees F. Increased seed output occurs when planting the sunflower in the early spring vs. late summer, when the harvest has a chance to occur during an early and untimely frost.

Harvesting

• The plant is ready for harvest when the flower head's back begins turning brown. If the seeds are not harvested timely, birds and disease may affect the plant. The plant takes time to dry enough for seed storage. The seeds are ready for long-term storage with 10 percent moisture content. Moisture content of up to 15 percent is suitable for short-term storage during freezing temperatures, but the seeds are likely to spoil when exposed to warm temperatures.