From the National Junior Horticulture Association:
Horticulture Essay Contest
This project is designed to stimulate youth interest in writing and research on horticultural subjects. It can be integrated into high-school English and research classes to make students more aware of the scope and opportunities in horticulture.
Who Can Participate
15-18 and 19-22 years old, individuals.
A 1500-2000 word paper with at least five references.
Deadline September 15.
More info here.