Castor bean: femme fatale of the plant world

“The castor bean plant is the most deadly of all plants. Eat a single castor bean, or perhaps two if you're an adult, and you'll die — maybe. If you live beyond three to five days, you will probably survive.”

So says USA Today, the authoritative source on all things scientific. OK, I’m being facetious—I love sensationalism as much as the next guy.

Ricinus communis ‘Carmencita’
Photo courtesy of Wikimedia Commons

There is no denying that the castor bean plant (Ricinus communis) is the botanical equivalent of a black widow spider, but its deadliness is concealed in a most attractive package. In just one season, it grows from a seed the size of a bean into a tree-like shrub that can reach 10 ft. in height if conditions are favorable. Its hand-shaped leaves with deeply cut lobes give it a distinctly tropical look that I find irresistible. It can be grown pretty much anywhere in the United States as an annual, allowing even gardeners in notoriously chilly climes to add a touch of the exotic to their garden.

What makes the castor bean plant so poisonous is a chemical called ricin. I won’t go into detail as to how it works and what effects it has; you can read all about it in this article from Cornell University’s Department of Animal Science.

Castor bean seeds.
It looks like they’re going to germinate even though they’re not in soil.

Notwithstanding these obviously negative characteristics, I have wanted a castor bean plant for a long time. A fellow blogger was kind enough to send me some seeds, and I planted two of them in 3” pots a few weeks ago. They have sprouted since then, and while the seedlings don’t look much like the adult plant, I’m impressed with their vigor. I will put them in the ground this weekend—in a spot tucked away from the rest of the yard in order to keep out prying eyes and curious hands. While the leaves aren’t as toxic as the seeds, every part of the plant is considered poisonous. But so are tomato leaves, angel’s and devil's trumpets (brugmansias and daturas) found in many gardens, not to mention oleander grown by the thousands in the median strip of Northern California freeways.

Castor bean seedling

A bit of common sense should go a long way toward keeping everybody safe. For my part, I will remove all but one or two flower clusters as soon as they emerge. I only want a few seeds for next year in case I decide to do it all over again then.

Wikipedia has a lot of information about the the castor bean plant, castor oil, and ricin.

Also check out this humorous article about a Orem, UT gardener who was questioned by Homeland Security for growing a castor bean plant in his front yard. This is one of those News of the Weird-type stories you come across on the web.

And finally don’t miss this intriguing article about a woman from Eureka, CA who has a “horticultural Death Row” in her garden.


  1. My neighbor was told by a friend that putting castor bean seeds into the ground will "take care of" moles. I'm not sure if he meant deter or kill, but I gave him dozens, and dozens of seeds last year (I have hundreds left). It will be interesting to see how many castor beans are growing in his yard this year. :-)

  2. Alan, I came across references to that as well (deterring underground critters somehow). Some people claimed it works, others said it doesn't.

    Based on my extremely limited experience, the germination rate of fresh seeds must be very high. Or maybe it was because I used fluffy and fertile soil and water it well :-).

  3. They are a pretty plant. I use the castor oil pellets to deter moles and voles. I have heard the plant itself really does not help, but I have not tried it.


Post a Comment