Grow castor beans in locations that offer abundant sunlight and humid conditions, and harvest the plants once their seed pods are dry and begin to crack. To harvest, clip the dried seed pods from the plant before cracking them open to collect the seeds. Wear gloves during collection, and discard any seeds too small to germinate.
Plant castor beans in the spring once the risk of frost has passed. Clear an area that offers full sunlight, loosen the soil to depth of 8 inches, and cover the top inch with compost. Plant the castor seeds 2 inches deep, and space plants 18 inches to 3 feet apart to provide adequate growing room. Keep the soil moist to encourage germination. Seeds typically sprout 10 to 20 days after planting.
Water plants frequently during growth, but do not add fertilizer to the soil. Fertilizing the soil may decrease the seed yield and produce plants that are top-heavy and lack the root structure to support their own weight. Continue to water the plants throughout the summer, and collect seed pods once they have dried. Take care when handling plants as all parts of the castor bean plant contain a powerful toxin known as ricin.