Should You Grow the Castor Bean Plant?

Q. I have a question about a plant that I find very intriguing: the Castor Bean Plant. I had seen a few in my neighborhood and finally tracked a plant down in nearby Ottsville, PA, thinking I'd hit the jackpot. I planted it in a spot I thought it would like judging from the others I'd seen, and it has thrived right outside my back door. Then I read an article about the plant in my favorite local paper, The Bucks County Herald, and was horrified! The described toxicity of the beans (though they are beautiful to look at) really scared me! I had known nothing about the beans being poisonous; I just loved the way the plant looked and how it added contrast to the garden.

I had just passed on some seeds to my Mom, and as soon as I finished the article I called her to say "Don't touch them again until I talk to Mike McGrath!" I even had anxiety dreams about it, as we have four children, a beloved dog, and this plant is right outside our back door. The children are ages 6 to 12, so they know better than to ingest a bean, and the dog doesn't go into my garden that often. Am I over-reacting to think I should I rip this specimen out of the ground and have my Mom toss the seeds? Seeing the word 'Ricin' in the article literally scared me silly. My mom and I would love to hear your thoughts on this, and we always appreciate your words of wisdom and humor.

---Gayle in Doylestown, PA

Let's begin with what it is—a dramatic tropical plant that can easily grow ten feet tall in a season with huge colorful leaves as big as dinner plates. Because it is tropical, Gayle doesn't have to worry about the one she planted, as it died from frost shortly after she wrote us back in October. (In frost free climes they can become small trees.)

The plant has a surprisingly long history, with Lawrence Griffith's fine book "Flowers and Herbs of Early America" (published by the Colonial Williamsburg Foundation in 2008 in association with the Yale University Press) citing references to it as far back as the third century BC. Early Egyptians apparently used oil pressed from the notorious seeds in their lamps, and Thomas Jefferson is known to have deliberately planted it in areas where he hoped it would live up to its folklore and deter moles. (And, true to his famously competitive nature, he carefully nurtured one show-off specimen to a height of 22 feet.)

Unfortunately Jefferson probably learned that making George Washington extremely jealous was pretty much all the plant would do, as it seems to be universally acknowledged that a castor bean plant growing in soil does not deter moles. But some studies suggest that a specific form of castor oil distilled from the beans does repel moles, voles and other underground pests when applied to the soil. (As with medicinal castor oil, the poisonous ricin is removed during the distillation process.)

And yes, it really is ricin in the beans—the same deadly poison used in a famous political assassination involving a trick umbrella and in numerous terrorist incidents.

So, has Gayle endangered her mother by sending her those Seeds of Death (which look, by the way, like beautifully-colored engorged dog ticks)? Nope. I found the seeds listed for sale in several 2012 catalogs—all with the warning to keep the seeds away from children, but otherwise touted as a dramatic tropical ornamental(especially some of the subspecies, which sport wildly colored leaves).

The seeds are perfectly safe to handle, as they have a heavy protective coating that must be broken to release any of the nasty bits. Some sources even say that you could swallow the seeds without ill effect as they would simply pass through you, and that you'd have to chew them to be poisoned. (We do not suggest putting this advice to the test.)

Dr. Gerald Klingaman, retired horticulturist for the University of Arkansas Extension in Little Rock (and a frequent guest on our show), once named the castor bean his 'plant of the week' and called it a great choice for garden mavericks who like big, bold statements. He noted that while the toxicity of the beans was well established, he could find no reports of any ill effects from accidental poisonings—only use of the active ingredient in murder plots.

Since many of the worries I hear gardeners express are about the possibility of small children being 'castorized', I called the world-renowned Children's Hospital of Philadelphia and was put in touch with Dr. Kevin Osterhoudt, Medical Director of their Poison Control Center, Attending Physician in their Division of Emergency Medicine, and editor of "Pick Your Poison", a great feature that appears in the journal Pediatric Emergency Care, in which physicians send in case reports of kids who show up in the emergency room after ingesting something and you, the reader, try and guess what it was from their symptoms. (The culprit is frequently a plant part, and so we will definitely try and get this guy on our show in the future!)

Dr. Osterhoudt was kind enough to send us the details of the four children who had been rushed to Children's after ingesting castor beans in the last ten years. The age range of the inquisitive youngsters was tight—all were between 15 and 24 months of age, and all four were suspected of ingesting a single bean. None of the four experienced any symptoms, despite two of them having chewed the beans!

In a follow-up phone call, Dr. Osterhoudt stressed that these happy outcomes should not be seen as a sign of safety. More beans or more susceptible children might have led to different consequences, he notes; and even children who show no immediate symptoms should be monitored for potential future liver problems.

But does Philadelphia speak for the nation, I wondered? So I also contacted the American Association of Poison Control Centers, who kindly searched their data base and reported that poison information centers around the nation received 110 calls about "exposure to castor beans" in 2010, but that there were "no major effects" reported as a result of those exposures. (Dr. Osterhoudt included the 2009 national data with his information, and it was strikingly similar—212 'exposures' with no major toxicity.)

An official Canadian government site on poisonous plants (can you tell by now that I used to be a medical reporter?) notes that there have been cases of livestock poisoning (the beans are used as an ingredient in 'feed cakes' and apparently the manufacturing process can go badly wrong) in addition to the well-known implication of the bean's ricin in terrorist and murder plots. Then they offer what may be the best piece of advice for those who want to grow this striking specimen without worry—don't let the plants set seed. If you're concerned about the seeds, pull off all the flowers as they form, pull off immature seeds as they form and just enjoy the massive leaves.

As we've always stressed on the show, teach children not to eat strange things, and don't grow plants with poisonous parts if you have small children or dogs that seem to chew on everything.

Otherwise, plant the seeds directly in the ground after all risk of frost is gone, in rich, well-drained soil, and see if you can beat Jefferson's twenty-two footer.