Castor beans are the seeds of the tropical castor plant, Ricinus communis. U.S. farmers have largely stopped growing castor plants because the seeds and leaves are extremely toxic. Greases, machine lubricants, paints and pharmaceutical supplies all use castor oil as a component. Whether you need bulk seed or a small package is determined by whether you intend to grow enough plants for oil pressing or a few for ornamental garden use.
Buy seed online or through local garden centres, farm supply stores and nurseries. Ask your local extension office for reputable seed suppliers. Local extension offices are listed by state and county in the U.S.
Buy seed with the highest germination rate from suppliers with USDA-compliant seed labels carrying the name Ricinus communis. Seed from online auctions or barter sites may not be viable and may not even be castor beans. Reputable suppliers like Park Seed guarantee that their seed will perform as advertised.
Check seed labels, online and catalogue descriptions for sell-by dates, seed origin, plant characteristics and disease resistance. Reputable catalogue/online suppliers like Johnny's Seeds include this information. Species, variety name, seed lot, where seed was grown and weight after drying are provided by the seed supplier and included on seed packets and bags.
Buy certified seed to get exactly the variety you want, with no banned harmful weed seeds. Certified seed is grown under strict standards to keep the plant variety pure.
Buy seed packaged for the current year. Up to 50 per cent of old seed may not sprout. Using old seeds you run the risk of producing spindly, slow-growing plants that will not set seed.
Buy seed to arrive for planting in early May. For good seed production, use a planting rate of 6.35kg/acre (about 15.6kg/hectare). Buy enough seed to meet this rate over your entire planting area.
Castor plants can reach 40 inches across and up to 15 feet high depending on variety. Plant extra seeds because castor beans have a low germination (sprouting) rate. Make sure you have at least 140 warm growing season days.
Keep castor bean plants fenced to prevent children, pets or livestock from eating the seeds or leaves. Ricin in the seeds and leaves is seven times more deadly than cobra venom, according to USDA experts. Keep loose castor beans out of the reach of children and animals. If accidental poisoning is suspected, call your local poison centre immediately. Cornell University Department of Animal Science notes that horses are particularly vulnerable to castor bean poisoning. Do not plant castor beans close to grazing areas or barns. Castor beans are listed as weedy or invasive by the some states.