With oversized, tropical-looking leaves and bizarre seed pods, castor bean is an exotic addition to the ornamental garden. The only member of the genus, Ricinus communis is in the Spurge Family (Euphorbiaceae). The name of this plant comes from the Latin word for “tick,” which was used because the seeds look a bit like a certain species of European tick. Castor bean comes from tropical east Africa, around Ethiopia. It has spread to become a weed in many tropical and subtropical places around the world, including the southwestern U.S. S. Most plants grow in disturbed areas with moist, well-drained soils, like along riverbeds and roadside, as well as in fallow fields and on the edges of cultivated lands. Castor bean is an evergreen herbaceous or semi-woody large shrub or small tree. This tough, tender perennial can grow up to 40 feet tall. In places that don’t get frost, the stems will turn woody after a few years. It is easy to grow as a warm season annual in mild climates because it grows quickly and strongly, but it rarely gets taller than 6 to 10 feet in a single growing season. At first, this fast-growing plant tends to grow straight up. Later in the season, it will add branches to form a well-shaped shrub with strong stems and a dense canopy. The plant is killed when the temperature drops below 32F. This plant doesn’t have milky latex sap like many others in the euphorbia family. Instead, it has a watery sap. The alternate, star-shaped leaves on long petioles can grow over 2½ feet across. Each palmate leaf has 5 to11 deeply incised lobes, with serrated edges and prominent central veins. While the species’ leaves are glossy and green, cultivated types may have leaves that are black-purple, dark red-metallic, bronze-green, maroon, or bright green with white veins. Flowers are produced in dense inflorescences 8-18″ tall at the tops of the stems. The monoecious plants produce male flowers below the terminal female flowers. The flowers do not have petals and are not particularly showy. Each ½-inch male flower has a group of many cream or yellow stamens that spray a lot of pollen into the air. They senesce soon after shedding their pollen. The three conspicuous, star-shaped stigma lobes of the female flowers are bright red with feathery branches. Once the flower is pollinated, its small, spiny ovary turns into a fruit or seed capsule about the size of a golf ball. The seed pods may be green, pink, or red (depending on the variety), but gradually age to brown. Each round seed capsule has a lot of soft, flexible spines all over it, and it has three parts that separate when the seeds are ready. Each section contains one seed that is ejected, often with considerable force, when the carpel splits open. If the growing season is long enough (140 to 180 days), a lot of the ½-inch long seeds, which are sometimes called “beans” but aren’t really beans, are made. The shiny, mottled seeds are very pretty. They come in black, gray, brown, yellow-brown, maroon, and white, and each has its own design. Each seed has a small, spongy caruncle at one end which helps absorb water for germination when planted. Seeds remain viable for 2-3 years. Heavy oil, yellow or almost colorless, makes up about half of the seed’s weight. This oil has been used in many industrial settings. In the past, the oil was used to light lamps. Today, it is used to make paints and varnishes, water-resistant coatings, high-performance motor oils, soap, inks, and plastics. Other derivatives are used in polishes, as solid lubricants, in synthetic perfumes and other products. Plants are grown commercially in India, Brazil, and some parts of the United States to make oil. S. and other countries. Plants should be kept out of reach of children because the seeds are very poisonous. If you are worried about this, you can cut off the flowering spike. Ricinol, which is found in castor seeds, is one of the most poisonous natural substances. It is thought to be 6,000 times more poisonous than cyanide and 12,000 times more poisonous than rattlesnake venom. A normal-sized adult can die from eating as few as four seeds. Eating less will make them vomit, have severe abdominal pain, diarrhea, and seizures. Livestock and poultry can also be affected if they consume seeds or meal from the seeds. Although it is a very potent poison, ricin has been investigated as an anti-cancer agent. The ricin chemical dissolves in water but not in lipids (oils), so it stays in the “seed cake” after pressing. This waste is turned into a high-nitrogen fertilizer, or the meal can be fed to animals after being cleaned of its chemicals. Castor oil can be eaten and has been used medically to treat everything from heartburn to constipation because the toxin is not in the pure oil. It works well as a laxative or cathartic, and it can also be used on the skin to soothe dryness. Castor bean can be planted directly in the garden in late spring if it is grown for its looks, or it can be started indoors earlier (6–8 weeks before the average last frost) and moved outside when the weather gets warmer. Nick or scarify the seeds or soak overnight for better germination. Sow the seeds 1-1½ inches deep. 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. Place the plants outdoors in full sun and deep, rich soil about 4 feet apart. Provide plenty of water and fertilizer to achieve the largest size. Once established it can tolerate drought. Wind can shred the leaves, so they should be placed in a protected spot if possible. This plant doesn’t need much care besides being pruned to keep it from getting too big or staked if it’s too heavy at the top. Castor bean has few pests, although spider mites can sometimes be a problem in hot, dry weather. With its large leaves and tall stature, castor bean makes a bold statement in the garden. The coarse texture contrasts well with finely textured plants. Castor bean can be grown as a single plant to make a dramatic focal point in the landscape, or it can be grown in groups for a tropical look in the back of beds or near water features. You can grow it in big pots on patios or use it to make a temporary screen or privacy fence. Castor bean combines well with cannas, bananas and elephant ears for a tropical garden. Or use it as a backdrop for grasses and other large-scaled annuals for a more traditional look. A range of varieties have been selected for their leaf or flower/fruit colors, and for oil production. Some of the most common ornamental types include:
Gardeners looking to add drama and intrigue to their outdoor spaces would do well to consider Ricinus communis ‘New Zealand Black’. With its large, deep purple leaves and height up to 15 feet, this plant makes a bold statement in any garden bed or container. Let’s take a closer look at what makes ‘New Zealand Black’ castor bean such a standout ornamental plant.
Ricinus communis, commonly called castor bean or castor oil plant, is a fast-growing tropical perennial that is often cultivated as an annual in temperate climates. It is native to tropical Africa but grown worldwide for the oil extracted from its seeds
The castor bean plant can reach up to 15 feet tall in a single season. Its stems and leaves contain toxic compounds, making the plant potentially poisonous to people and pets if ingested. However, with reasonable care, it can be safely grown in gardens.
What Makes ‘New Zealand Black’ Unique
Ricinus communis ‘New Zealand Black’ is a cultivar selected for its striking dark reddish-purple foliage The leaves are so deeply colored as to appear nearly black. This makes a dramatic contrast against other green foliage.
In addition to its saturated leaf color, ‘New Zealand Black’ features:
- Huge leaves up to 20 inches wide
- Reddish stems and leaf undersides
- Tall height up to 15 feet
- Bright red flower spikes in summer
- Spiny red seed pods in fall
Overall, its exceptional size, rich coloration, and tropical look give this castor bean cultivar unmatched visual impact.
Growing Conditions for ‘New Zealand Black’
‘New Zealand Black’ thrives in warm climates and requires a long growing season. It prefers hot, sunny conditions with well-draining, fertile soil. Key tips for success:
- Start seeds indoors 8-10 weeks before last frost
- Transplant outdoors after danger of frost has passed
- Space plants 2-3 feet apart in full sun
- Provide regular water and fertilizer during growing season
- May grow as an annual or be overwintered indoors in cold climates
- Stake tall plants to prevent toppling
Using ‘New Zealand Black’ as a Striking Garden Specimen
Thanks to its height and bold coloring, ‘New Zealand Black’ makes an excellent accent or specimen plant. It draws the eye and adds dramatic contrast when surrounded by lighter greens.
Here are some suggested uses in the landscape:
- Anchor a tropical-themed bed or border
- Create vertical interest against a fence or wall
- Highlight entranceways and corners
- Make a living screen or hedge
- Grow in containers on a patio or deck
So if you’re looking to add an exotic, eye-catching element to your garden, be sure to consider Ricinus communis ‘New Zealand Black’ castor bean. This magnificent plant will transform any space into a tropical paradise!
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The Killer Bean: The Castor Bean Plant
FAQ
Are castor beans legal in the US?
What is Ricinus communis good for?
Is Ricinus communis poisonous?
Is Ricinus communis invasive?
What are the different types of Ricinus communis?
There are several varieties of Ricinus communis (castor oil plant). Ricinus communis var. gibsonii is a smaller (in comparison) castor oil plant and can be used towards the front of the border without causing too much imbalance.
What genus is Ricinus communis?
The only member of the genus, Ricinus communis is in the Spurge Family (Euphorbiaceae). The word ricinus is Latin for “tick”, used for this plant name because of the superficial resemblance of the seeds to a particular species of European tick.
What is the difference between carmacita and Ricinus communis?
Ricinus communis ‘Carmacita’ and ‘Carmacita pink’ have red and pink seed pods, whereas other varieties of Ricinus communis do not. The Carmacita pink variety gives the plant a slightly sickly appearance.