Castor Bean
Often grown as an annual, the caster bean is a tender perennial. It can grow 6-10 feet tall in a single season but will die when temperatures reach freezing. In frost-free areas, it can reach up to 40 feet tall! It is an attractive ornamental plant that should be grown with care. It is poisonous, so it may not be ideal for places with pets and children.
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Red Spire |
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Ricinus communis |
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Intermediate-Easy |
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Intermediate |
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2-3 years if properly stored |
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Perennial |
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7-21 days |
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7-10′ |
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Full sun |
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140-180 days |
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April and May |
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No |
Growing Tips
Spring: After the danger of frost is over.
Transplant: Start seedlings 6-8 weeks before transplanting.
Nick or soak seeds overnight to aid with germination. Plant in full sun 1-1½ inches deep. Soil should be loamy, moist, but not soaking wet, soil for best results. Seedlings should start coming up in 1-3 weeks. The young plants grow quite quickly and may need repotting into larger containers before transplanting outdoors.
After hardening off, transplant them 4 feet apart as they will get quite large. Once established it can tolerate drought. However, wind can shred the leaves, so they should be placed in a protected spot if possible. Plants can be pruned to limit their size, and staked if top-heavy; otherwise, this plant needs very little maintenance.
Flowers will form later in the season. The plant will produce both male and female flowers. The female will develop into a spiney seed pod that will brown and later split open shooting the seed away from the mother plant. It will also produce beans that are attractive. The seeds are extremely poisonous as they contain the toxin, ricin.
Seed Saving
The seed pods will start to fade and eventually turn brown. Allow castor bean pods to dry on the plant so that the seeds have plenty of time to mature. Eventually, the seed pods will split open, which is a sure sign that it’s time to start collecting castor seeds.
To collect castor bean seeds, first, clip the dried seed pods from the plant. Castor seed pods are very prickly, It is recommended to use gloves to handle them. You can store the seeds right in the pod, or remove the seeds from the pods before storing them.
To collect castor plant seeds, break open the seed pods. There are three castor seeds per seed pod. Sometimes not all the seeds in the pod are large enough to keep. Discard any castor bean pods or seeds that are small, they won’t be mature enough to germinate.
Special Considerations
- The seeds are poisonous. The alluring seeds are tempting to young children. Therefore, growing castor beans in the home landscape is not a good idea if you have children or pets. It should be noted, however, that the toxins do not pass into the oil.
- Only compost if your compost pile reaches 140 F. This is the temperature Ricin will break down. Otherwise don’t compost.
- It can grow to 40’ tall in frost-free environments, but the plant is killed if the temperatures dip below 32F.
Sources:
University of Wisconsin-Madison: hort.extension.wisc.edu
Gardeningknowhow.com
getbusygardening.com/how-to-collect-castor-bean-seeds/