It depends. Usually doesn't take very long. The most important thing is to keep a good eye and harvest before it shatters and the seeds fall off.
Félix LabboN'Djamena
Chosen answer:
Fonio grows very rapidly, it depends mostly on the type. The most common variant, white fonio, takes approximately 6 to 8 weeks after planting. The less common black fonio takes around 24 weeks.