Castor bean is a fast-growing, suckering perennial shrub or small tree from the Horn of Africa, grown widely as an ornamental and for castor oil. It is frost-tender and grown as an annual in cold climates, but it is highly poisonous because its seeds contain ricin.
Family
Euphorbiaceae (Spurge family)
Grows as
Perennial
Light
Full sun
Water
Water regularly during growth and let the top layer of soil dry slightly between waterings.
Soil
Fertile, well-drained garden soil or rich potting mix.
Temperature
20–30 °C; protect below 10 °C, as it is not cold hardy.
How easy
Easy
Safety
Toxic: Seeds contain ricin, a highly potent toxin; even a few raw beans can be fatal, and the pollen and sap can cause severe allergic reactions and skin rashes.. Toxic to cats and dogs (ASPCA).
Native range
NE. Trop. Africa
Climate
seasonally dry tropical
About
Ricinus communis, the castor bean or castor oil plant, is a species of perennial flowering plant in the spurge family, Euphorbiaceae. It is the sole species in the monotypic genus, Ricinus, and subtribe, Ricininae.
Its seed is the castor bean, which despite the term is not a bean (as it is not the seed of a member of the family Fabaceae). Castor is native to the Horn of Africa, but it is now widespread throughout tropical regions (and widely grown elsewhere as an ornamental plant).
How to grow it
It is also used extensively as a decorative plant in parks and other public areas, particularly as a "dot plant" in traditional bedding schemes. If sown early, under glass, and kept at a temperature of around 20 °C (68 °F) until planted out, the castor oil plant can reach a height of 2–3 metres (6.6–9.8 ft) in a year. In areas prone to frost it is usually shorter, and grown as if it were an annual. However, it can grow well outdoors in cooler climates, at least in southern England, and the leaves do not appear to suffer frost damage in sheltered spots, where it remains evergreen. It was used in Edwardian times in the parks of Toronto, Canada. Although not cultivated there, the plant grows wild in the US, notably Griffith Park in Los Angeles.
Safety
Ricinus is extremely allergenic, and has an OPALS allergy scale rating of 10 out of 10. The plant is also a very strong trigger for asthma, and allergies to Ricinus are commonplace and severe.
The castor oil plant produces abundant amounts of very light pollen, which easily become airborne and can be inhaled into the lungs, triggering allergic reactions. The sap of the plant causes skin rashes. People who are allergic to the plant can also develop rashes from touching the leaves, flowers, or seeds. They can also have cross-allergic reactions to latex sap from the related Hevea brasiliensis plant.
Where it grows
Although R. communis is indigenous to the southeastern Mediterranean Basin, Eastern Africa, and India, today it is widespread throughout tropical regions. In areas with a suitable climate, castor establishes itself easily where it can become an invasive plant and can often be found on wasteland.
Uses
Global castor seed production is around two million tons per year. Leading producing areas are India (with over three-quarters of the global yield), China and Mozambique, and it is widely grown as a crop in Ethiopia. There are several active breeding programmes.
[Contains information from Leaf Area Index (LAI) and Heritage Trees from data.gov.sg (National Parks Board), made available under the terms of the Singapore Open Data Licence version 1.0]
Text excerpted from the Wikipedia article Ricinus by its contributors, under CC BY-SA 4.0; the excerpts and the care summary drawn from them are shared under the same licence.
The care summary was written by AI (Claude, Anthropic) from the sources on this page, with general growing knowledge where they are silent. Check before relying on it.
Life form, climate and native range: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 3.0), reformatted; see Plants of the World Online.