Growing the indigo plant is not difficult as exotic as it may seem. Originating in India, the indigo plant is used to make the dye that shares its name. It is mentioned in a manuscript dated to the fourth century B.C. Indigo is the dye once used for denim. Artificial varieties are used now, although true indigo dye is making a comeback.
Indigo does well if kept in an area that gets bright light, but is also warm. A windowsill is a good location if it is not too drafty. Unless you live in a climate similar to India’s, don’t keep this plant outdoors; it will not withstand cold temperatures. Indigo prefers moist, well drained soils, so be sure to water regularly throughout its growing season, April through September, but a little less in the cooler months. Feeding with a high potassium fertilizer will encourage blooms. If the soil seems less able to hold water than usual, it’s probably time to repot your indigo. Spring is a good time for this, just before the growing season begins. The best time to prune depends on what your goals are. To encourage flowering, prune in May or June. If you are using the leaves to make dye, you can prune anytime in summer.
If you can’t find indigo plants in stores, like other members of the legume family, it is relatively easy to grow from seed. May is a good time to do this. Place seed in a starter pot filled with good quality potting soil, and then sprinkle a fine layer of soil over the top. Water well, and then cover with a sheet of glass or plastic dome to retain warmth and moisture, and keep in a warm area. As the plant grows, carefully re-pot in larger containers. Once the plant has reached maturity, take cuttings from your plant, root them, and share with friends.