The Effect of Temperature on the Germination of Sunflower Seeds

Sunflower seeds germinate at specific temperatures.

The sunflower (Helianthus annuus L.) is a cheerful addition to any garden. Quick and easy to grow, the sunflower seems foolproof. But, it is important to remember that planting sunflower seeds at the appropriate temperature is key to proper germination.

Optimal Temperatures

Often overlooked, correct temperature is essential for sunflower seed germination. Soil and environmental temperatures affect the number of seeds that germinate and the speed at which they grow. Sunflower seeds have an optimal temperature requirement of 70 to 78 degrees Fahrenheit, though temperatures ranging from 64 to 91 will not make a noticeable difference on productivity.

High Temperature

Temperatures that exceed 91 degrees Fahrenheit will greatly hinder sunflower seed germination, the rate of germination and seed viability. Germination can occur at temperatures exceeding 100 degrees but is no longer possible at 113 degrees.

Low Temperature

The sunflower plant is more tolerant of lower temperatures. Germination has occurred at temperatures as low as 39 degrees Fahrenheit, but growth is more likely to occur between 46 and 50 degrees. Once germination has been set in motion, dips in temperature to 23 degrees will not hinder germination.

References

• Purdue University: Alternative Field Crops Manual: Sunflower
• Science Direct: Effects of Temperature and Oxygen on Seed Germination and Seedling Growth in Sunflower (Helianthus annuus L.)
• "California Master Gardener Handbook": Dennis R. Pittenger, Editor