Indigo (Indigofera tinctoria) is a small, subtropical, perennial shrub from the Fabaceae (pea) family. It has been cultivated for chemicals in its leaves that yield blue or violet dye depending on how it’s processed. Indigo is now naturalized in Asia, Africa, and Southern United States.
Indigo grows about six feet tall and has pink or violet flowers in clusters that appear in early summer and yield two-inch seed pods that resemble string beans in late summer. The leaves are pinnate and pale green. Both leaves and flowers are typical of the pea family in appearance.
Other Names True Indigo, Black Henna, Indigofera
History and Folklore
No one is sure where indigo originated since it has been cultivated around the world for so long, but India is the top candidate.
Indigo can be grown as a perennial in the Southern United States but as an annual in most places with a mild season. It makes excellent nitrogen-fixing cover crop and also kills nematodes in the soil.
Indigo needs full sun and good drainage in somewhat alkaline soil. You will need to rub the seeds briefly between two pieces of sandpaper and then soak for 24 hours before planting. Plant indigo seeds about 1/4 inch deep and 12 inches apart. Thin to three feet apart after the first true leaves appear.
Harvesting & Storage
Cut the leaves away when the plant is in full flower. Use fresh.
The indigo plant has been used in Eastern Medicine to treat ovarian cancer, epilepsy, and nervous conditions.
Indigo is poisonous and should not be ingested.