Castor Oil Plant 10/20cm (P9)

The Castor Oil Plant – Ricinus communis – is one of the most theatrical foliage plants you can grow in a British garden, delivering a truly tropical punch from a single season’s growth. Native to north-east Africa and western Asia, it has been cultivated for centuries both for its striking ornamental value and for the oil pressed from its seeds. Grown as an annual in the British climate, it rewards gardeners with an extraordinary display of bold, glossy, deeply lobed leaves that can span up to 30cm across, held aloft on dramatic red stems. Foliage comes in rich shades of green, deep bronze, and reddish-purple depending on the variety, making it an outstanding structural plant for exotic-style planting schemes and summer borders alike.

This is a plant that commands attention. The large, palmate leaves — each divided into five to twelve pointed lobes — create a lush, almost jungle-like canopy that sits beautifully alongside hot-coloured perennials and contrasting tropical foliage such as cannas, dahlias, and bananas. As summer progresses, upright spikes of small, yellowish-green flowers emerge, followed by the plant’s most eye-catching feature: bright red, spherical, spiny seed capsules that add a quirky textural detail to borders and containers. The overall effect is one of effortless exotic drama.

Ricinus communis thrives in a warm, sheltered spot in full sun. In gardens, it should be planted out only after all risk of frost has passed — typically late May to early June — into fertile, humus-rich, well-drained soil. It performs well in borders and large containers alike, making it excellent for patio displays. Regular watering is essential throughout the growing season; do not allow the compost or surrounding soil to dry out completely. Feed with a balanced liquid fertiliser every month to support the plant’s vigorous growth and encourage lush, colourful foliage. In exposed positions, staking is advisable, as the large leaves can act like sails in strong winds.

Plants grown in poorer soils tend to divert energy into flowering rather than foliage, so enrich the planting site generously with garden compost before planting. Deadhead or remove developing seed capsules if you wish to avoid seed set — this is particularly recommended as the seeds are highly toxic if ingested, as indeed are all parts of this plant. Always wear gloves when handling Ricinus communis and keep it well away from children and pets.

⚠️ Important safety note: All parts of Ricinus communis are highly toxic if eaten, including the seeds. This plant should be handled with care and is not suitable for gardens frequented by young children or pets.

Ultimate height
1.5–2.5 metres

Time to ultimate height
1 year

Ultimate spread
0.5–1 metres