Germination temperature
Warm; the plant grows best at about 20-28 °C (68-82 °F) and is frost-tender.
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Physic nut is a tough, drought-tolerant shrub or small tree used for living fences and oil-seed plantations, and it grows readily from seed in warm climates. Its seeds are poisonous, so this guide starts with safe handling before covering soaking, sowing depth, nursery time and pruning.
Warm; the plant grows best at about 20-28 °C (68-82 °F) and is frost-tender.
2-4 cm (0.8-1.6 in) in nursery bags; 4-6 cm (1.6-2.4 in) when sown directly in the field.
6-15 days if kept well watered.
Full sun.
Soak for 12 hours before sowing.
Nursery seedlings establish far better than direct sowing; plant out after 2-3 months at 30-40 cm (12-16 in).
Jatropha seeds are poisonous. The World Agroforestry database warns that the kernel is toxic and that eating seeds causes severe vomiting and purging; larger amounts can be dangerous. Never eat the seeds, store them out of reach of children and animals, wash your hands after handling them, and do not use them as toy beads. If anyone swallows seeds, seek medical help immediately.
Choose large, plump seeds. FAO advises putting seed in water and discarding any that float. Freshly harvested seed can be dormant: World Agroforestry reports high viability but low germination shortly after harvest, and FAO uses seed dried and stored for at least a month for direct sowing.
Optional. Nicking or softening the seed coat improves germination, but a simple soak works as well or better: in FAO trials nicking or a cold-water soak gave about 72% germination.
Not needed. Jatropha is a tropical plant with no cold requirement.
Recommended. TNAU soaks seed for 12 hours in water or cow dung solution. In FAO trials a 12-hour soak in cow dung slurry gave about 96% germination.
Sow in warm weather. No exact germination temperature is published, but the species grows best at mean temperatures of 20-28 °C (68-82 °F) and tolerates only slight frost. In India, FAO's timing (sowing about three months before the rains) means a nursery in the hot pre-monsoon months.
One seed per bag, 2-4 cm (0.8-1.6 in) deep with the small caruncle (the pale bump at one end) facing down (FAO). In the field sow two seeds per spot 4-6 cm (1.6-2.4 in) deep and thin to one.
TNAU fills 10 x 20 cm polybags with red soil, sand and farmyard manure 2:1:1. Avoid heavy soils, which restrict root formation.
Keep evenly moist until emergence, but do not let water stand: damping-off in nurseries is linked to poorly drained soil and poor ventilation (TNAU).
Germination does not need light. Grow seedlings in full sun with good air movement.
FAO gives 6-15 days in well-watered conditions; in TNAU's raised nursery beds germination starts around day 3.
Plant out after two to three months, when seedlings are 30-40 cm (12-16 in) tall and before the taproot is cramped in the bag (FAO). Plant at the start of the rains into holes 30-45 cm (12-18 in) wide and deep, spaced 2 x 2 m to 3 x 3 m (6.5-10 ft) apart; wider spacing gives more yield per plant.
Keep the young plants weeded; seedlings compete poorly with weeds. TNAU makes the first pruning at 6-8 months, cutting back to 45 cm (18 in), and keeps pruning for three years to build a bushy frame.
Cause: dormancy shortly after harvest. Fix: dry fresh seed and keep it for a few weeks before sowing, then soak for 12 hours.
Cause: damping-off, favoured by crowded sowing, wet soil and poor ventilation. Fix: sow one seed per bag in free-draining mix and water only as needed.
Cause: millipedes (which can destroy whole batches of seedlings) or termites. Fix: raise seedlings off the ground on a clean surface and keep the nursery free of rotting debris.
Cause: shield-backed bugs feeding on flowers and young fruit. Fix: check plants during flowering and remove the bugs early.
Cause: jatropha can host cassava viruses. Fix: remove badly affected plants and do not take cuttings from them.
Animals avoid the toxic foliage, which makes physic nut a classic hedge. Cuttings planted directly in the line root easily, but seedlings form a deeper taproot.
Nursery-raised plants first bear after their first rainy season, direct-sown plants after the second, and full productivity comes at about three years (World Agroforestry).
Jatropha is very drought tolerant. TNAU gives a life irrigation on day 3 after planting and then every 20-25 days in dry weather.
Physic nut spreads easily and is restricted as a weed in some countries, so check local regulations before planting outside its existing range.
Raise physic nut in bags for a tough, drought-tolerant hedge; the seeds are not edible.
Yes. The seeds and oil are toxic; eating them causes severe vomiting and diarrhoea and larger amounts can be dangerous. Keep seeds away from children and livestock and wash your hands after handling.
Yes. A 12-hour soak in water or cow dung slurry is standard; FAO trials reached about 96% germination with the slurry soak.
Freshly harvested jatropha seed can be dormant. Let it dry for a few weeks first. Seed also loses viability with age: World Agroforestry reports below 50% viability after 15 months.