How to Grow Castor Oil Plant
Ricinus communis
⚠️ TOXIC — all parts, especially seeds, are poisonous to humans, cats, dogs, and livestock. Grow Ricinus communis for its dramatic tropical foliage, not for harvest. Sow seeds indoors in individual pots in early spring (March–April), soaking for 24 hours first. Germination takes 2–3 weeks at 18–24°C. Grow on in a warm bright place and harden off carefully. Plant out after all frost risk has passed, in a sheltered, sunny, rich border. Plants can reach 2 m or more in one UK summer. Water freely and feed fortnightly. Remove developing seed pods promptly to reduce toxicity risk. Discard plants at season end — they are killed by the first frost.
When to Start
Start seeds indoors 8 weeks before your last frost date. Transplant outdoors once night temperatures stay above 10°C and soil has warmed to at least 15°C.
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Growth Stages
Approximate days from start
Care Essentials
- Apply a balanced liquid feed every two weeks from late spring through summer to support vigorous growth.
- ⚠️ TOXIC — All parts of Ricinus communis are poisonous to humans, cats, dogs, and livestock. The seeds contain ricin, one of the most toxic naturally occurring substances known. Never allow children or pets near this plant. Wear gloves when handling and wash hands thoroughly afterwards. Do not grow where children or pets have unsupervised access. Ricinus is grown purely as a dramatic foliage annual. Its enormous palmate leaves — bronze-red or deep green depending on cultivar — can reach 60 cm across and give tropical impact to borders and containers. Plants grow 1.5-3 m in a single season in UK summers. Deadhead the spiky seed pods as they form to reduce toxicity risk and prevent self-seeding.
Growing Conditions
- Min. soil temperature
- 15°C+
- Germination temperature
- 18–25°C
Pet Safety
- Sow indoors
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- Transplant out
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Spacing & Planting
| Plant spacing | 120 cm |
| Row spacing | 120 cm |
| Sow depth | 2.5 cm |
| Mature height | 200 cm |
| Mature spread | 150 cm |
Growing Conditions
| Min. soil temperature | 15°C |
| Germination temperature | 18–25°C |
| Base growth temperature | 10°C |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Castor Oil Plant?
- Plant Castor Oil Plant 120cm apart with 120cm between rows.
- Is Castor Oil Plant frost hardy?
- Castor Oil Plant is classified as Tender.
