Castor Bean, Castor Oil plant. A striking tree-like plant to 15' often grown in gardens for effect - the handsome leaves are up to 3' wide and palmately divided into 5 To 11 crenate lobes. It is also grown in northern zones in summer. Fast growing. Seeds poisonous if eaten. Easily grown. Plant the seeds at 1" depth using a well draining soil mixture. Provide bright light and keep lightly moist.