True indigo Indigofera tinctoria
True indigo (Indigofera tinctoria) is an evergreen perennial shrub in the Fabaceae family, native to Tropical Africa and Asia (exact origin unclear after long cultivation). It grows 1–2 m (3.3–6.6 ft) tall and 60 cm–1.2 m (24 in–3.9 ft) wide, wants full sun and moderate water, and is hardy to about 5 °C (41 °F). Space plants about 60 cm (24 in) apart.
Plan True indigo in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
True indigo at a glance
| Type | Perennial shrub, evergreen |
|---|---|
| Family | Fabaceae |
| Mature height | 1–2 m (3.3–6.6 ft) |
| Mature spread | 60 cm–1.2 m (24 in–3.9 ft) |
| Spacing | 60 cm (24 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Moderate; drought tolerance moderate, waterlogging tolerance none |
| Soil pH | 5.5–7.5 |
| Cold hardiness | About 5 °C (41 °F) once established (roughly USDA zone 11) |
| Heat stress | Likely above about 40 °C (104 °F) |
| Flowering | about 13–21 weeks after planting, for 9–17 weeks |
| Wind tolerance | Low |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | Tropical Africa and Asia (exact origin unclear after long cultivation) |
| Common in gardens of | 🇮🇳 India, 🇮🇩 Indonesia, 🇹🇭 Thailand, 🇻🇳 Vietnam, 🇳🇬 Nigeria, 🇪🇹 Ethiopia, 🇺🇸 United States |
Is True indigo toxic?
- People: not well documented
- Cats: not well documented
- Dogs: not well documented
- Parts: leaves, seeds
No reliable toxicity data; several other Indigofera species poison livestock, so do not let animals graze it.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with True indigo
Good neighbours
- good With Sweet corn: "Three sisters": climbing beans use corn as a support and fix nitrogen; the benefit to the corn is modest but real in low-input soils. Evidence C
Keep apart or take care
- caution With Alliums (onion family): Onions, garlic and leeks are said to stunt beans and peas (allium root exudates may reduce nodulation). Traditional companion-planting advice; controlled trials are few, so treat it as a soft preference. Evidence D
- caution With Alliums (onion family): Beans and peas are traditionally kept away from onions, garlic and leeks. Traditional companion-planting advice; controlled trials are few, so treat it as a soft preference. Evidence D
- caution With Fennel: Fennel is reported to suppress beans and peas growing next to it. Evidence C
Questions about True indigo
- How far apart should I plant True indigo?
- About 60 cm (24 in) apart, centre to centre. A mature plant spreads 60 cm–1.2 m (24 in–3.9 ft).
- Does True indigo need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does True indigo need?
- Moderate water. Drought tolerance is moderate and waterlogging tolerance none.
- How cold-hardy is True indigo?
- It tolerates about 5 °C (41 °F) once established, roughly USDA zone 11.
- When does True indigo flower?
- About 13–21 weeks after planting, for 9–17 weeks.
- Is True indigo poisonous to cats and dogs?
- For cats it is not well documented; for dogs not well documented; for people not well documented. No reliable toxicity data; several other Indigofera species poison livestock, so do not let animals graze it.
- What grows well with True indigo?
- "Three sisters": climbing beans use corn as a support and fix nitrogen; the benefit to the corn is modest but real in low-input soils.
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- Natural Dyes: Sources, Tradition, Technology and Science (Cardon, 2007), Archetype Publications, London
- PROSEA: Plant Resources of South-East Asia, PROSEA Foundation, Bogor
Notes and assumptions
- The indigo of India: leaves steeped and oxidised give the deep blue that made colonial Bengal plantations infamous (the Indigo Revolt of 1859). A nitrogen-fixing shrub, often grown as a short-lived crop cut twice a year. Frost-tender.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Bush bean Phaseolus vulgaris
- Garden pea Pisum sativum
- Sweet pea Lathyrus odoratus
- Runner bean Phaseolus coccineus
- Broad bean (fava) Vicia faba
- Lima bean Phaseolus lunatus
- Cowpea (black-eyed pea) Vigna unguiculata
- Yardlong bean Vigna unguiculata subsp. sesquipedalis