Indigo, True Indigo, dye indigo
Indigofera tinctoria

Family: Fabaceae

What it is like

True Indigo or Indigofera tinctoria is a perennial plant reaching a height of 1-2 m upon maturity. Branches are spreading or ascending and are often woody. The leaves are pinnate. It is one of the major sources of deep blue dye. Medicinally, it is used to treat a wide range of disorders such as epilepsy, nervous disorders, asthma, bronchitis, fever, stomach pain, liver diseases, kidney and spleen diseases, skin conditions, wounds sores, hemorrhoids, gonorrhea, syphilis, snake bites, etc. The plant is also used as cover crop and green manure. It also has a symbiotic relationship with certain soil bacteria that form rood nodules and fix atmospheric nitrogen.

Indigofera tinctoria is a deciduous Shrub growing to 2 m (6ft) by 2 m (6ft) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 6. It can fix Nitrogen. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.

Height (m): 2

Where it is found

Not known

Probably originally from Malaysia, the plant now has a pantropical distribution.

Conservation Status: This taxon has not yet been assessed

Countries/locations it is found in

Africa, Asia, Burkina Faso, Burma, East Africa, East Timor, Ethiopia, Guiana, Guinea, Guinée, Guinea-Bissau, Guyana, Haiti, India, Indochina, Jamaica, Malaysia, Mozambique, Myanmar, Pakistan, Philippines, SE Asia, Sri Lanka, Suriname, Thailand, Timor-Leste, Venezuela, West Africa, West Indies, Zambia,

How it is used

Food

Rating: 2

The deep blue dye obtained from the leaves is sometimes used to counteract the slightly yellow colour of icing sugar.

Colouring: edible dyes

Medicine

Rating: 2

A leaf infusion (sometimes combined with honey or milk) is used to treat a range of disorders including epilepsy and nervous disorders; asthma and bronchitis; fever; complaints of the stomach, liver, kidney and spleen; and as a rabies prophylactic. Applied externally, the leaves are made into an ointment for treating skin diseases, wounds, sores, ulcers and haemorrhoids. A tincture of the seed is used in India to kill lice. A root preparation is applied to relieve toothache, syphilis, gonorrhoea and kidney stones. A watery root paste is applied topically in India to treat worm-infested wounds. A root infusion is used there as an antidote against snakebites and to treat insect and scorpion stings.

Antiasthmatic: Treats asthma.

Antihaemorrhoidal: Treats haemorrhoids (piles). This would probably be best added to another heading.

Epilepsy: Used in the treatment of Epilepsy - a disorder in which nerve cell activity in the brain is disturbed, causing seizures.

Febrifuge: Reduces fevers.

Kidney: Used in the treatment of kidney diseases

Mouthwash: Treats problems such as mouth ulcers.

Skin: Plants used in miscellaneous treatments for the skin.

Stings: Used in the treatment of stings and insect bites.

Stomachic: Aids and improves the action of the stomach.

Other

Rating: 4

Agroforestry Uses: The plant is sometimes grown as a cover crop and green manure. Indigofera tinctoria is useful as a green manure, it is used in India, for example, in coffee plantations and as a cover crop preceding rice, maize, cotton and sugarcane. In traditional rainfed rice cropping systems in the Philippines, this plant is a popular green manure, increasing rice yield whilst also reducing by 50% the need to supply expensive nitrogen fertilizer. The residue remaining after indigo extraction is also applied to the land as manure. Another reason to grow Indigofera tinctoria as a green manure is because it is a good nitrogen catch crop, reducing the amount of fertilizer NO3 leaching to the groundwater. Other Uses: A deep blue dye is obtained from the leaves. The leaves and twigs do not actually contain indigo but colourless precursors that must be extracted and then processed in order to produce the indigo dye. The harvested leafy branches are placed in a tank containing water to which some lime has been added, and are weighted down with planks. After some hours of fermentation, during which enzymic hydrolysis leads to the formation of indoxyl, the liquid is drained off and then stirred continuously for several hours to stimulate oxidation of the indoxyl. Afterwards the solution is left to rest and the insoluble indigo settles to the bottom as a bluish sludge. The water is drained and after the indigo has dried, it is cut into cubes or made into balls. To dye textiles, indigo is reduced to a soluble form by a fermentation process under alkaline conditions. In traditional preparations of the dye, various reducing agents such as molasses are used, together with coconut-milk, bananas and the leaves of Psidium guajava. The alkalinity is maintained by adding lime. After the textile has been dipped into solution it turns blue when exposed to the air. The twigs are used as toothbrushes.

Dye: Plants that provide dyes.

Green manure: Fast-growing plants that can be used to increase the fertility of the soil.

Insecticide: Kills insects.

Soil conditioner: Plants grown to improve the structure of the soil. See also Green manures.

Teeth: Plants used to clean and care for the teeth.

Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.

Industrial Crop: Dye: Botanical dyes replacing synthetic dyes (known as heavy polluters).

Management: Coppice: Cut to the ground repeatedly - resprouting vigorously. Non-destructive management systems maintaining the soil organic carbon.

Minor Global Crop: These crops are already grown or traded around the world, but on a smaller scale than the global perennial staple and industrial crops, The annual value of a minor global crop is under $1 billion US. Examples include shea, carob, Brazil nuts and fibers such as ramie and sisal.

Agroforestry Services: Nitrogen: Plants that contribute to nitrogen fixation include the legume family – Fabaceae.

Industrial Crop: Dye: Botanical dyes replacing synthetic dyes (known as heavy polluters).

Management: Coppice: Cut to the ground repeatedly - resprouting vigorously. Non-destructive management systems maintaining the soil organic carbon.

Minor Global Crop: These crops are already grown or traded around the world, but on a smaller scale than the global perennial staple and industrial crops, The annual value of a minor global crop is under $1 billion US. Examples include shea, carob, Brazil nuts and fibers such as ramie and sisal.

Carbon Farming: Plants that can be a critical part of the solution to climate problems. The Carbon Farming Solution - Eric Toensmeier.

Coppice: A traditional method of woodland management which exploits the capacity of many species of trees to put out new shoots from their stump or roots if cut down.

Food Forest: Plants for Edible Forest Gardens and Food Forests.

Nitrogen Fixer: Plants that fix nitrogen in the soil

How it is grown

A plant of the tropics and subtropics, where it is found at elevations up to 1,600 metres. It grows best in areas where annual daytime temperatures are within the range 22 - 28°c, but can tolerate 7 - 32°c. It prefers a mean annual rainfall in the range 1,300 - 1,700mm, but tolerates 640 - 3,000mm. Requires a position in full sun, succeeding in any deep, well-drained and moderately retentive and fertile soil. Prefers a pH in the range 6 - 7, tolerating 4.3 - 8.7. Requires a position sheltered from hot winds. Branches are harvested by cutting 10 - 20cm above ground level when the plants are 4 - 5 months old and have formed a closed stand, usually at the flowering stage. The crop should be harvested promptly because heavy rains or flooding can destroy it in a few hours. In India harvested branches are tied into bundles of about 130 kg and transported to the dye factory. Up to 3 harvests are possible per year. Dye yields can be 1.6 - 5.4 tonnes per hectare. This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby. Flowering Time: Mid Spring. Bloom Color: Red-Orange or Pink. Spacing: 36-48 in. (90-120 cm).

Propagating it: Seed - pre-soak overnight in warm water and sow in a seedbed with partial shade. Germination takes about 4 days. Semi-ripe cuttings of lateral shoots with a heel. Root cuttings.

Best place to grow:

Habit: Shrub

Hardiness: 5-12

Growth: Fast

Soil: Light (sandy), medium, heavy (clay)

Shade: Semi-shade, no shade

Moisture: Moist

Things to keep in mind

Its other names

Local names

dye indigo, Indian indigo, indigo, Indigostrauch - German, nanban-ai - Japanese Romaji, indigo - Swedish. Baludo, Banhebe, Banhepe, Bno, Caro, Carodim-o, Caromessem-o, Carre, Darko, Gara, Garatchendo, Ipute, Tinta, akika, amari, aviri, avuri, avuri (whole plant), avuri ver (root), añil, dye indigo, gali, galiparna, gari, indian indigo, indigo, indigo plant, indigostrauch, indigotier, kadu avuri, kadunili, karunili, kondannili, kalkesi, nanban-ai, neel, neela amari, neelamar, neeli, neeligida, nil, nila, nilam, nilbam, nili, nili chettu, nilika, nilini, nili, nilini, nilpu?pa, nili (leaf), nili (root), nili (whole plant), nilika, nilini, olleneeli, qing dai, rangapatri, rangapatri, true indigo,

Synonyms

Anila tinctoria normalis Kuntze Indigofera anil orthocarpa DC. Indigofera bergii Vatke Indigofera ci