Quick Overview
*Depends on variety, leaf freshness, fermentation, and aeration quality.
| Parameter | Recommendation |
|---|---|
| Rainfall | 800–1,800 mm/year |
| Sunlight | 6–8 hours/day full sun |
| Soil Texture | Loose, well-drained; avoid waterlogging |
| Spacing | 60×60 cm (dye garden); 80×80 cm (agroforestry) |
Growing Conditions & Varieties
Indigofera tinctoria and Strobilanthes cusia are two popular indigo sources. In tropical regions, Indigofera tinctoria is adaptive and productive.
Recommended Varieties
- I. tinctoria (tropical indigo): easy to grow, high adaptability, ideal for bulk dye production.
- S. cusia (assam indigo): strong color quality, preferred for artisan dye; slightly more care-intensive.
Nursery Preparation
- Seed selection: use certified seeds or collect from healthy mother plants; soak 8–12 hours for faster germination.
- Soil mix: compost : soil : sand (1:1:1), sterilized by sun-drying or light baking.
- Sowing: sprinkle thinly, cover lightly with soil; keep moist but not waterlogged.
- Seedling care: gradual sun exposure; harden 3–5 days before transplanting.
- Transplant age: 3–4 weeks, 10–15 cm tall, 4–6 true leaves.
Planting & Care
Land Preparation
- Till 20–30 cm deep, create ridges and drainage ditches.
- Add well-decomposed compost 5–8 tons/ha.
- Lime application if pH < 5.5 (1–2 tons/ha dolomite).
Spacing & Planting System
Commonly 60×60 cm. For agroforestry integration: 80×80 cm between shade trees.
Maintenance
- Watering: maintain moist soil, avoid flooding.
- Weeding: every 2–3 weeks during early growth.
- Fertilization: compost + vermicompost or light NPK doses.
- Pests & diseases: aphids, leaf caterpillars; use neem or BT biopesticide if needed.
Harvest & Yield
- First harvest: 3–4 months; subsequent harvests every 2–3 months (coppicing system).
- Harvested parts: shoots & leaves; avoid woody stems.
- Handling: process within 6 hours after harvest to preserve indican content.
Expected Yield
| System | Fresh biomass/ha | Indigo paste |
|---|---|---|
| Intensive organic | 12–18 tons | 50–120 kg |
| Moderate conventional | 8–12 tons | 30–80 kg |
Fermentation & Indigo Making
The goal is to convert leaf indican into insoluble indigo pigment via fermentation & oxidation.
Basic Equipment
- Plastic/fiber tanks (200–1,000 L)
- Leaf baskets/net
- Aeration tools (blower/bucket pour)
- pH meter/strips, alkali (lime/soda ash)
- Cloth filters, simple press
Process Steps
- Leaf soaking: water:leaf ratio 5–7:1, 12–18 hours, pH 5.5–6.5. Filtrate turns yellow-green.
- Alkalization: raise pH to 10–11 using alkali, prepare for oxidation.
- Aeration/oxidation: stir/pour for 20–40 mins until liquid turns deep blue & fine sediment appears.
- Settling: rest 8–12 hours; collect sediment, filter, wash.
- Drying: shade-dry to 10–15% moisture → indigo paste/cake.
Pros & Cons
| Pros | Challenges |
|---|---|
| Eco-friendly, high market value | Low yield, labor intensive |
| Premium price for artisan/eco brands | Batch variability |
Economics & Estimated Costs
| Component | Estimate/ha (IDR) |
|---|---|
| Seeds & nursery | 3–5 million |
| Fertilizers & soil amendments | 6–10 million |
| Labor (land prep–harvest) | 12–18 million |
| Fermentation equipment | 5–12 million |
| Total year 1 | 26–45 million |
*Indicative figures; adjust to local conditions. Artisan indigo paste sells at IDR 400–900k/kg depending on quality.
We can help design SOP, QC, and color benchmarks.
FAQ: Indigo Cultivation
How many times can indigo be harvested in a year?
Usually 3–4 times, depending on climate & management. After the first cut, new shoots regrow for the next harvests.
Is organic cultivation possible?
Yes. Use compost, vermicompost, biofertilizers (PGPR), and biopesticides. Consistency depends on good nutrient & water management.
How to store indigo paste?
Keep in sealed containers, cool & shaded. Avoid contamination with heavy metals and direct sunlight.