Samia ricini is polyphagous, which is much of its practical advantage: over twenty species will support a crop, so ericulture can be fitted to whatever a holding already grows. Castor and kesseru carry the commercial system.
Host plant tiers
| Tier | Species |
|---|---|
| Primary | Castor (Ricinus communis L., Euphorbiaceae); Kesseru (Heteropanax fragrans Roxb. Seem., Araliaceae) |
| Secondary | Tapioca (Manihot esculenta); Payam (Evodia fraxinifolia); Borkesseru (Ailanthus excelsa); Borpat (A. grandis); A. glandulosa; A. tryphysa |
| Tertiary | Over twenty species including papaya (Carica papaya), gamari (Gmelina arborea), gulancha (Plumeria acutifolia), champa (Michelia champaca), jackfruit (Artocarpus heterophyllus), ber (Zizyphus mauritiana) and Zanthoxylum spp. |
Castor and kesseru: cultivation norms
| Parameter | Castor (annual) | Kesseru (perennial) |
|---|---|---|
| Preferred varieties | NBR-1 and NBR-2 for ericulture; state-recommended varieties and hybrids for dual-purpose cultivation (local red and local green in the North East) | HF-005 and HF-008 high-yielding selections |
| Soil | Loamy, well drained, humus-rich; avoid water stagnation | Loamy, well drained |
| Spacing | 1 × 1 m irrigated; 1 × 0.6 m dryland | 3 × 3 m |
| Density | 4,000 – 10,000 / acre depending on spacing | About 444 – 450 / acre |
| Pit (L × B × D) | 20 × 25 × 25 cm | 25 × 25 × 25 cm |
| Nutrients | Rain-fed 40–60 : 30–50 : 15–30 kg NPK/ha; irrigated 90–120 : 50–60 : 30–40 kg NPK/ha. Nitrogen in three equal splits — basal, 35–40 days and 65–70 days after sowing, by ring application | 125 : 75 : 25 from the second year in two split doses; FYM 0.5 cft/pit rising to 1 cft when mature |
| Harvests per year | 4 | 3 |
| Gestation | Same season | 3 – 4 years |
| Canopy management | — | Pollarded at 1.75 m from year 3, at 3-year intervals |
Castor yields in the same season it is sown; kesseru takes three to four years. That single
difference decides which a household plants — castor for immediate return and
flexibility, kesseru for a standing asset that needs less annual work once established.