Earth & Sky

Sunflower

DB: This is Earth and Sky, with a questions we recorded at San Francisco’s Exploratorium.

Jose Serrano: Hi, my name is Jose Serrano, and I come from Seaside, California, and my question is how long do sunflowers live?

JB: Jose, even though sunflowers can easily grow taller than 18 feet – about five and a half meters – they never live longer than a year. A sunflower that starts growing in spring will die soon after it drops its seeds the following fall. The exact length of the growing season varies with geography and local weather.

DB: The simple sunflower has been used to help trace the history of human civilization. The long-standing view held that Native Americans in the U.S. were the first to domesticate sunflowers sometime before 1200 BC. But in Tabasco, Mexico, scientists have found fairly large sunflower seeds in the soil dating back to 2800 BC. The large seeds are significant because wild sunflowers tend to have smaller seeds.

JB: Experts are now analyzing sunflower DNA from across North America to find the true source of the first domesticated sunflower – possibly to reveal new insights into how and when civilizations evolved. Thanks for your question, Jose. And thanks to the U.S. Forest Service and to the National Fish and Wildlife Foundation – supporting the conservation of native fish, wildlife, plants and their habitats. We’re Block and Byrd for Earth and Sky.