Grow campus history: Red sunflower seed pick up begins April 16
The Cockerell red sunflower as seen on the CU Boulder campus
As CU Boulder celebrates its 150th anniversary, the University Libraries are inviting you to plant a living piece of that history—a red sunflower cultivated locally 115 years ago by CU Boulder professor Theodore Dru Allison Cockerell and his wife, high school biology teacher Wilmatte Porter Cockerell. Through their pioneering work, the remarkable flower became part of the region’s botanical heritage. Today, thanks to the University Libraries One Seed program, descendants of that sunflower are now grown across campus and in the backyards of many in the community.
Red sunflower seeds will be available on April 16 and 22 inside the East Entrance of Norlin Library from 1 p.m. to 3 p.m. both days. Seed packets can also be picked up at the Ask a Librarian desk in Norlin and each of the campus libraries’ service desks starting April 16.
Since One Seed began in 2021, the Libraries have distributed over 7,200 seed packets to the community for them to grow in their own gardens—an approximate 108,000 red sunflowers. The project explores the red sunflower’s historical ties to CU Boulder, and the scientific aspects of this unique plant.
"One Seed offers a chance to reflect on how library collections have shaped the uniqueness of experiences here for 150 years,” explained Abbey Lewis, STEM Engagement Librarian and founder of the program. “Throughout the university’s history, students have been exploring our materials and finding things that connect with their daily lives, their dreams and their interests."
Planting tips from CU Boulder’s horticulturists
Sunflowers can be easy to grow particularly if planted in the right conditions. However, for gardeners looking to increase their success rate, CU Boulder horticulturists Christian Parker and Jason Wiley offer a few tips for growing a taller and redder flower.
“Sunflowers grow best in full sun, however they can do reasonably well with at least 6 hours of morning sun or 4 hours of afternoon sun,” said Parker. “They are quite happy in poor soil conditions, and will respond well in any Colorado soil, whether it’s been amended with compost/fertilizer or not. Although they are very drought tolerant, for the best and largest plants/blooms, I would recommend daily watering until they are about 2 feet tall, and then pulling back to 2 – 3 times a week watering schedule (depending on current temperatures). One important thing to consider is location. These plants have shallow roots, but also get to be ten feet in height. So finding a spot in an area that is protected from high winds will help ensure that they do not break off at the root.”
Genetics are the biggest factor for how red—or yellow—the sunflowers will ultimately be. To cultivate a redder flower for future years, Wiley suggests that gardeners, “hand-pollinate only the red flowers with a watercolor paintbrush and save seeds only from those plants. To increase your chances further, remove or clip nearby yellow-flowered sunflowers. You can sow seeds more densely than needed, then thin by pulling out the yellow ones as they bloom.”
The origins of the red sunflower
In 1910, Wilmatte Porter Cockerell, a high school biology teacher, noticed a red sunflower growing in the wild across the street from her home in Boulder. Along with her husband, Theodore Dru Allison Cockerell, a professor at the University of Colorado Boulder, Cockerell transplanted the sunflower into her own garden.
The flower was a "sport," a spontaneous mutation resulting in morphological differences in a plant. With their backgrounds in the sciences, the Cockerells knew that sunflowers are unable to be fertilized with their own pollen, and so experimented in cross-pollinating the sunflower with others until the desired red color was visible in the flower's offspring.
The Cockerells were able to sell seeds carrying the red mutation to seed companies and were recognized at the 1915 Panama-Pacific International Exhibition for their work in cultivating the unique flowers. The many varieties of red sunflowers available all over the world today are believed to be descendants of the one carefully tended by the Cockerells in Boulder, Colorado.
The University Libraries Archives holds 60 linear feet of physical archival materials from the Cockerells, including the original red sunflower—now nearly a century old. Elements of the T.D.A. Cockerell Collection have been digitized and can be found via the CU Digital Library.