Growing Castor Beans (Ricinus) in Southern Ontario

Castor beans love heat and sun. In Ajax (Zone 5b), start seeds indoors under 18-hour lights, but transition outdoors once nights stay above 10°C (50°F).

Hardening Off & Planting

• After May 24 (last frost), place seedlings in protected shade for 10 days.
• Plant in full sun (8+ hours); they tolerate partial shade.
• Water regularly for fastest growth; they reach 10–12 feet.
• Feed with balanced 12-12-12 fertilizer per label.

All plant parts are toxic—keep away from children and pets. The tropical foliage makes a dramatic annual screen.