Starting in the sixth century, the Japanese began using natural ingredients to dye clothing. The most common color was an array of rich, deep indigos extracted from the leaves of an exotic plant known as tade ai. Farm workers began relying upon indigo dye, or aizome, specifically because it had antibacterial and insect-repellent effects, helping their clothes last longer. Progressively, this became a sustainable fashion trend throughout Japanese culture. The Morikami Museum and Japanese Gardens in Delray Beach will explore the history and applications of aizome in “Out of the Blue: Japanese Indigo Textiles,” a new exhibition opening October 19. “Indigo is used in a lot of different parts of society,” says Tamara Joy, chief curator at the Morikami. “Not only is it beautiful, functional, and practical, it has a lot of strong symbolic associations.” Joy explains that indigo in a range of shades can be seen in many categories of garments, with several examples appearing in “Out of the Blue.” A circa-1920 fisherman’s festival jacket boasts an indigo background decorated with cranes and turtles, representing longevity. Firemen wore dark blue coats with interior details of protective images, such as warriors and dragons. Even samurais lined their armor with a cotton dyed in indigo in honor of its association with strength.