Especially if started indoors in late winter, a row of castor can grow into an effective screen hedge. The entire plant is mildly toxic and has been proven in university tests to repel moles. However, after making sprays of vivid red, spikey flowers, it produces large brown beans that are highly toxic to small children, pets and livestock-especially horses. The seed pulp inside the tough, waterproof skin contains castor oil, the familiar purgative, plus a water-soluble toxin called ricin that is so poisonous to animals it is used as an organic pest control and is suspected as an agent of biological warfare. It is best not to grow castor anywhere children or domestic animals can get to it.
Castor oil is sold in any drug store.