Jatropha curcas aka Physicnut

Jatropha curcas is a fast-growing plant that typically reaches 15-20 feet (4.5-6 meters) tall with a spread of 10-15 feet. Plants propagated from cuttings tend to fruit even faster than seed-grown plants, though they develop shallower root systems.

Jatropha curcas thrives in warm tropical to subtropical temperatures between 65-85°F (18-29°C), with optimal growth occurring at 68-79°F (20-26°C). The plant is frost-sensitive and temperatures below 50°F (10°C) can cause damage or be fatal. It's hardy to USDA zones 9-11 and can tolerate brief, slight frost once established, though prolonged cold will cause leaf drop and potential die-back.

Jatropha curcas is highly adaptable to varying humidity levels and actually prefers low to moderate humidity typical of arid and semi-arid environments. The plant thrives in its native dry savannah and thorn forest habitats where humidity is naturally low. While it can tolerate higher humidity in tropical regions, it does not require frequent misting or elevated moisture levels, making it an excellent choice for dry indoor environments.

Jatropha curcas produces small yellow-green flowers in spring on monoecious inflorescences, meaning both male and female flowers appear on the same plant. Each inflorescence typically has 10-20 male flowers for every female flower. The flowers are followed by green seed pods that mature to yellow-red, each containing 2-3 oily black seeds. Flowers form on terminal growth, so heavy pruning can reduce flowering.

Yes, there are distinct varieties of Jatropha curcas, most notably the toxic and non-toxic forms. The standard variety contains phorbol esters and is highly poisonous, but non-toxic edible varieties native to Mexico are known locally as piñón manso, xuta, chuta, and aishte. These edible varieties have been traditionally cultivated for their safe-to-eat seeds and are distinct from the toxic commercial forms grown for biodiesel production.

Jatropha curcas thrives outdoors in USDA hardiness zones 9-11, where it grows as a small tree or large shrub reaching up to 20 feet tall. It's native to tropical and subtropical regions and excels in warm, frost-free climates with full sun exposure. The plant is widely cultivated outdoors in tropical areas worldwide for biodiesel production and as living fences, and it tolerates poor soils and drought conditions once established, making it ideal for marginal landscapes.

Jatropha curcas can be pruned to maintain shape and size, but timing is important since flowers and fruit form on terminal growth (branch tips). It's best to prune lightly after flowering and fruiting to avoid reducing seed production. The plant is commonly pruned when grown as a hedge or living fence, and it responds well to shaping. Avoid heavy pruning during the active growing season as this will remove flowering sites.

Repot Jatropha curcas when it has doubled in size or when roots begin emerging from drainage holes, typically every 2-3 years for young plants. Use well-draining soil and a pot only slightly larger than the previous one. The plant develops a deep taproot when grown from seed, so choose a pot with adequate depth. Spring is the ideal time for repotting, just before the active growing season begins.

Wipe Jatropha curcas leaves gently with a soft, damp cloth to remove dust buildup. The 3-5 lobed, maple-like leaves can accumulate dust indoors, which reduces photosynthesis efficiency. Avoid using leaf shine products as they can clog the leaf pores. Always wear gloves when handling the plant, as the milky latex sap can cause skin irritation and all parts are toxic if ingested.

Jatropha curcas can be propagated from seeds or stem cuttings. Seeds germinate within 9-10 days under good moisture and warmth; use fresh seeds for best results. For cuttings, take 20cm lengths from juvenile plants, preferably from basal branches, and treat with rooting hormone (200 μg/L IBA) for optimal results. Cuttings can be planted directly in well-draining soil and will fruit faster than seed-grown plants, though they develop shallower root systems.

Yellow leaves on Jatropha curcas typically indicate overwatering or poor drainage, as the plant is drought-tolerant and sensitive to waterlogged soil. Allow soil to dry out between waterings and ensure pots have adequate drainage. Yellowing can also occur naturally in fall when the deciduous plant prepares for dormancy. Nutrient deficiency, particularly nitrogen, may cause older leaves to yellow, though Jatropha tolerates poor soils well.

Brown leaf tips or edges on Jatropha curcas usually result from underwatering (despite drought tolerance, it still needs regular water during active growth), low humidity, or exposure to temperatures below 50°F (10°C). Brown spots may indicate fungal leaf spot diseases like Cercospora or Pestalotiopsis. Ensure adequate watering during the growing season while maintaining good air circulation, and protect plants from cold drafts or frost.

Drooping or wilting Jatropha curcas is most commonly caused by severe underwatering during the active growing season. While drought-tolerant, the plant still needs regular watering when actively growing in spring and summer. Overwatering causing root rot can also lead to drooping, as can sudden temperature drops below 50°F (10°C). Check soil moisture and adjust watering accordingly—soil should dry between waterings but not remain bone-dry for extended periods during active growth.

Jatropha curcas naturally drops leaves in fall and winter as it enters dormancy, being deciduous or semi-evergreen depending on climate. This is normal seasonal behavior. Excessive leaf drop during the growing season may indicate stress from overwatering, cold temperatures (below 50°F/10°C), sudden temperature changes, or insufficient light. The plant requires full sun and will drop leaves if light levels are too low.

Jatropha curcas is naturally a fast-growing plant, so slow growth indicates suboptimal conditions. Common causes include insufficient light (it requires full sun and cannot grow in shade), temperatures below 65°F (18°C), or winter dormancy when growth naturally pauses. Extremely poor soil can also limit growth, though the plant tolerates marginal conditions. Ensure the plant receives at least 6 hours of direct sunlight daily and warm temperatures for optimal growth.

Jatropha curcas is generally pest-resistant but can be affected by leaf beetles, spider mites, whiteflies, mealybugs, and leaf miners in intensive cultivation. Common diseases include collar rot and root rot (Fusarium, Rhizoctonia), leaf spot (Cercospora, Pestalotiopsis), powdery mildew, and damping off (Phytophthora). The plant is susceptible to over 35 fungal species when stressed. Good drainage prevents most root diseases, and the plant has no serious pest issues when grown in typical home conditions with proper care.

Jatropha curcas is pollinated by insects and is self-fertile, meaning individual plants can produce seeds without cross-pollination. The plant produces monoecious flowers with both male and female flowers on the same inflorescence, typically with 10-20 male flowers for each female flower. Indoor plants may benefit from gentle shaking or hand-pollination with a small brush to ensure fruit set, though this is usually not necessary outdoors where natural pollinators are present.

Standard Jatropha curcas is highly toxic and NOT safe to eat—the seeds are especially dangerous to children and can cause severe vomiting, diarrhea, and abdominal pain if ingested. However, non-toxic edible varieties exist in Mexico (called piñón manso, xuta, chuta, aishte) where young leaves, shoots, and properly prepared seeds are consumed after steaming or roasting. Unless you have confirmed non-toxic cultivars, treat all parts as poisonous and keep away from children and pets.

Jatropha curcas has traditional medicinal uses, but EXTREME CAUTION is required as all parts are poisonous. The latex has documented antibiotic properties against Candida albicans, E. coli, and Staphylococcus aureus. Traditional uses include: bark juice for malarial fevers, leaf infusions for coughs and rheumatic pain, seed oil for skin diseases and hair growth, and external applications for burns and eczema. However, internal use can be dangerous—consult healthcare professionals before any medicinal use.

Jatropha curcas has extensive non-food applications, earning a 4/5 rating for other uses. Seeds contain 30-40% oil used for biodiesel production (one square mile yields 2,000 barrels annually), soap, candles, varnish, and ink. The plant serves as living fences (unpalatable to livestock), erosion control, and support for climbing crops like vanilla. Seed press cake makes nitrogen-rich fertilizer (3.2-3.8% N), bark provides tannin for dyes and leather tanning, and the oil has pest control properties.