Spirulina species are primarily found in alkaline, warm freshwater lakes and lagoons. The three most important locations are Lake Chad in Central Africa, Lake Texcoco in Mexico, and Dongting Lake in China. Today, Spirulina is mainly cultivated in artificial aquaculture bassins or tube reactors worldwide.

In water, Spirulina appears as filamentous, spirally coiled colonies. Its color is intense blue-green to greenish. The individual filaments are microscopic (about 0.2–0.5 mm long), form loose mats, and float freely in the water

Spirulina is almost exclusively cultivated, not harvested in the wild. It is harvested by filtering the water in which the algae grow. After harvesting, the algae are washed and spray-dried. They are then packaged in a protective atmosphere.