How to grow castor oil plant

A native of tropical climates, ricinus is usually grown as an annual in the UK and suits both containers and borders.

How to grow castor oil plant

Grow castor oil plant in free-draining soil in full sun. Water plants regularly and feed with a liquid fertiliser every month. Plants may need staking. Deadhead flowers if you don’t want to collect the seed. At the end of the season, discard plants on the compost heap, or move plants to a covered area under glass to grow on as a conservatory shrub.

Where to grow castor oil plant

Grow castor oil plant in a well-drained sunny border or in containers of free draining, soil-based compost. Plants grown on poorer soils tend to produce more flowers and the foliage is less abundant.

How to plant castor oil plant

Please note, castor oil seeds are poisonous, so wear gloves when handling. Castor beans must be sown early in the year, and ideally soaked for a few hours beforehand. Fill individual pots with peat-free seed compost, sow the castor bean seeds and place in a heated propagator to germinate. Castor seeds need temperatures of 15-20°C to germinate, and should sprout in two to six weeks. Pot on when seedlings are large enough to handle and move outdoors or plant up into containers or borders when all danger of frost has passed.

Caring for castor oil plant

All parts of Ricinus communis are highly toxic so it’s very important to wear gloves when handling – it can irritate skin and eyes. Water plants regularly and feed with a liquid fertiliser every month. Plants are generally fast growing - Ricinus communis reaches 8-12m in height in tropical climes, but is much smaller in the British climate. As such plants may, or may not, need staking. Deadhead flowers if you don’t want to collect the seed. At the end of the season, discard plants on the compost heap, or move plants to a covered area under glass to grow on as a conservatory shrub.

Propagating castor oil plant

Ricinus communis produces greenish-yellow flowers and spiny round seedpods. You can save the seed but they are notoriously toxic. Bearing this in mind, you might choose to deadhead the blooms before seeds set.

Castor bean plant: problem solving

Ricinus is generally disease-free if grown outdoors. If grown under glass, it may fall prey to the usual greenhouse pests such as red spider mite.

Ricinus varieties to try

• Ricinus communis ‘Carmencita’ - with large, deep bronze-red, palmate leaves and bold red female flower spikes in summer
• Ricinus communis ‘Red Giant’- this variety has brighter red leaves and seed heads. Leaves appear green at first, turning red as they mature
• Ricinus communis ‘Impala’ - the foliage is typically striking, but in this variety, the flowers are equally eye-catching. They appear as clusters of creamy flowers and are followed by brilliant red spiky fruits