Castor Bean

Castor Bean is an ornamental with a tropical feel

For a tough, dependable, large plant that lends a tropical feel to beds we like the Castor Bean. Here in Cincinnatti, we treat it as an oversized ornamental with broad purple-red leaves that are shaped like stars—each one can reach up to two feet across. Sprigs of red flowers seem like they’ve been tucked in here and there to decorate the serrated foliage, and curious spiny seed pods complete the look.

This heritage plant has been cultivated for thousands of years

Castor Bean is another old is new kind of plant—one that your grandma planted but your mom probably did not. It’s an evergreen, semi-woody shrub, or small tree, that’s a member of the spurge family and native to tropical areas in east Africa. Over the years Castor Bean has naturalized in similar climates throughout the world. In some locations where the plant grows naturally it can actually be found as a weed in the moist soil along riverbeds and roadsides. 

Red female flowers develop spiky seed pods

Those feathery red blooms are actually female flowers that grow above cream-colored male flowers on the same plant. After pollination occurs the females develop the funky, golf ball-sized seed pods that contain the intriguing Castor beans. We call them beans but they are actually seeds that are about the size of pinto beans, in mottled patterns of black, gray, brown, beige, maroon, and white. Bear in mind: this is not an edible plant—like other tropicals it is poisonous to eat.

Castor beans are actually attractive, mottled seeds

Now, the Castor Bean plant has been grown for thousands of years. This is because about half the weight of the seed is oil that’s considered valuable within industry, originally for fueling lamps and eventually for a number of other applications. Castor oil has been used in the production of paint and varnish and is also an ingredient in high-performance motor oil, soap, inks, and plastics.

Both male and female flowers grow on the same plant

You might be wondering about the Castor oil your grandmother used as a health elixir and yes, it is one and the same. In its pure form the oil is not toxic but it does have to be processed, and it has been used medicinally as a cure-all for a long list of ailments through the years. At one time Castor oil was even thought to make a woman’s hair grow.

Castor Bean makes a bold statement in the garden

Like many of our tropicals, Castor Bean makes a bold statement in the garden. We like to group this variety in clusters of three or more to give it a fuller look. It can also be grown as a specimen for a centerpiece with exotic flare. This is a good plant to use at the back of beds or around a water feature, or for creating a screen or an interesting hedge. Castor Bean works well in large patio containers and combines easily with cannas, bananas, and elephant ears for a tranquil tropical oasis. When we want a more subdued effect we mix it with grasses or other large-scaled ornamentals.

Plants can reach around five feet high with plenty of water

This is a no-maintenance plant that can handle tough situations. It can get tall, around five feet or so if given plenty of water, but can remain shorter—around three and a half feet—if you run it drier. You can expect to end up with a nicely proportioned shrub that has a dense canopy over the top. Be sure to space these at least four feet apart. If plants get too large they can be pruned or staked for support. Once established, Castor Bean can handle a bit of drought.

Castor Bean is available in the 1-gallon pot.

Castor Bean can be an effective screen