How to grow indigo, the plant that produces the color jeans.

A plant already known to the Egyptians, indigo was one of the most famous dyes in history.

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La indigo plant It is grown mainly to obtain the famous natural blue dye called Indigo, traditionally obtained from the species Indigofera tinctoria. Indigo belongs to a genus of evergreen and deciduous shrubs, as well as herbaceous perennials, comprising 700 different species. The shrubby species are generally hardy, with compound leaves and papilionaceous flowers, pink or purple. They are medium-sized and can reach 2 meters in height. The most popular species tend to grow both tall and wide, resulting in a rounded shrub.

How it is grown

Indigo, already known to the Egyptians two thousand years before the birth of Christ (they used it in cosmetics and to dye fabrics), is a plant that, to be cultivated successfully, must respect its tropical origins. In fact, the places where it grows best are those where daytime temperatures range between 22 and 28 degrees Celsius and never drop below 6-7 degrees Celsius.

Exposure and climate

Indigo thrives in a Mediterranean climate and bright, even full sun, exposure. It's important that the plant, outdoors, be well protected from hot winds that can burn it. Indigo grows best in:

  • warm or subtropical climates
  • ideal temperatures: 20–35 °C
  • lots of direct sun

In cooler areas (such as much of Europe) it is grown in summer o in the greenhouse.

Land and cultivation care

It prefers soft, well-drained soil, slightly sandy or loamy, with a pH between 6 and 7,5. In spring, apply a fertilizer rich in nitrogen and potassium. In late winter, mix a generous amount of organic fertilizer into the soil around the plant.

Watering

Water abundantly, but only when the substrate is completely dry, leaving it dry for up to 2-3 weeks. 

Sowing and flowering

In March-April, indigo is sown in pots filled with seed compost, in a cold frame. The seedlings are planted the following spring. Flowering occurs from June to September, depending on the species. The flowers are pinkish-purple.  

How to get indigo color 

Indigo blue is not already visible in the plant. The dye is obtained through fermentation of the leaves:

  • leaves placed in water
  • fermentation
  • oxygenation
  • pigment precipitation
  • drying of the blue pasta

The result is indigo powder used for textile dyes (such as in jeans).

Uses of Indigo

Even today, as in the times of the Egyptians, the leaves of the plant are transformed into an ointment, useful against dry skin, but also for small wounds and even to treat the hemorrhoids. Furthermore, an infusion of leaves, combined with honey and milk, can prove useful for asthma, bronchitis and stomach problems. 

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