Fast-growing castor bean plants are worth growing for their immense, star-shaped burgundy or green leaves, which cast a spell of jungle magic over any garden. Because they are toxic, check out these quick tips and learn how to safely grow castor beans today!
Getting to know castor beans
- Castor bean’s strange clusters of bristly red or pink flowers open in late summer and are followed by round pods covered with colourful spines that contain bean-sized mottled seeds.
- In a warm summer with plenty of rain, these dramatic plants can reach three to 3.7 metres (10 to 12 feet) in height, with leaves up to 60 centimetres (25 inches) in diameter that may be bright green or bronze red, depending on the variety. I
- f you need a fast-growing screen to block bad views or a giant self-supporting hedge, or if you want to form a leafy background for a flower bed, no other annual or perennial will do the job like castor bean plants. And because the stems are spaced rather far apart, sufficient light reaches the insides of the plants to accommodate vines such as morning glories, which twine around the central stem for surprising special effects.
- Castor bean plants also work well as a leafy backdrop for larger-than-life flowering annuals, such as love-lies-bleeding (amaranth), tall zinnias or sunflowers.
Choosing the perfect castor bean
You’ll find that seed companies offer a few cultivars, but any gardener who grows castor beans will surely have a few seeds or volunteer seedlings to share.
- In the spring you can buy bedding plants from garden centres.
- The ‘Carmencita’ variety has very large, deep-mahogany leaves and unusually large, bright red flowers.
- ‘Carmencita Pink’ has pink flowers, while the flowers of Impala mix are carmine with maroon, followed by maroon seed pods.
Growing castor beans the safe way
- Start castor beans indoors 10 weeks before your last frost, taking care to wear gloves when handling the poisonous seeds. In areas with warm and long summers, you can plant the seeds directly outdoors.
- Soak the seeds for 24 hours in warm water before planting them 2.5 centimetres (one inch) deep in moist soil.
- Keep the soil moist and between 16°C and 21°C (61°F and 70°F).
- Sprouting, or germination, should begin within 15 days, and the seedlings can be planted out after the soil warms in late spring.
- Castor beans do not require fertile soil, but the garden spot where you plant them should be loose and crumbly for at least 30 centimetres (12 inches) deep so that the roots of seedlings can grow deeply. If their roots cannot penetrate the soil, a summer storm can blow these tall-growing beauties down. Space or thin seedlings to one metre (three feet) apart in the garden.
- Because castor bean seeds are poisonous, a strong case can be made for not growing them in gardens visited by children. As an extra safety precaution, you can snip off the flowers before they set seed pods and dispose of them, since the seeds are the only toxic part of the plants.
- To their credit, pests of all kinds avoid castor beans and also may ignore nearby plants. The seeds are widely believed to repel moles when dropped into mole tunnels.
Keep these tips in mind before you plant castor beans, and consult your local garden centre for more information about controlling the toxic plant.