Hello fellow readers, Last week, I shared the desperate measure of hacking back leatherleaf viburnums plagued with aphids. Ironically, Betsy from Stone Church PA asked about using castor beans plants in her garden, which is what I planted to camouflage the ‘uglies’ of the leafless sticks while the viburnums recover.
Are castor bean plants dangerously toxic?
Betsy heard castor bean plants are dangerously toxic. It’s true that technically all parts of the plant are considered poisonous if eaten. However, the seeds contain the highest concentration of ricin and are especially toxic. But then, many of our ornamental plants are toxic if ingested, such as azaleas, yews, and daffodils, to name just a few. If you review the list of poisonous plants, including the foliage of food plants such as onions, garlic, tomatoes, lima beans, and potatoes, you’d be nervous about planting many things. The bottom line, we should teach our children not to eat what’s not intended to be eaten.
Benefits of castor bean plants in the garden
Castor bean (Ricinus communis) is a tropical plant native to Africa, making a striking annual plant in our zone (5b or 6). The large leaves are reddish, and the plant grows 5 to 7 feet or more, creating a commanding presence in the garden. They prefer full sun or light shade and can handle most soil other than constant wet feet. However, their fuzzy flowers are not their finest feature and are hidden by their unusual foliage.
Thomas Jefferson cultivated castor bean plants to deter moles.
As I write, I am in Virginia tending to Mom, who gave me my garden start. She is in the last stages of dementia. Just three years ago, she was able to join in a tour of Thomas Jefferson’s Monticello estate in Charlottesville, VA. Jefferson was a collector of plants, and, as the tour guide explained, he left his mark in the history of horticulture ‘as a facilitator and champion of using plants as an agent for social change.’ Meaning, plants can facilitate a livelihood for those that cultivate them and, of course, provide food.
It’s fascinating to learn about Jefferson’s trials and tribulations. I heard he deliberately planted castor beans in hopes of deterring moles without success, though an oil distilled from the beans and applied to the soil may work. As with medicinal castor oil, the poisonous ricin is removed during the distilling process. Thomas Jefferson cultivated a castor bean plant to grow 22 feet tall, fitting for his competitive nature. Think of all the ‘uglies’ 22 feet could hide! Garden Dilemmas? firstname.lastname@example.org
A side note: I introduced castor bean plants to a longtime client who became a friend, thinking we found a sure win on deer resistance because of toxicity. It turns out the darn deer chomped the plants and spit them out. Barbara, who I joke moved to the Carolina’s to run away from her deer dilemma, hoped to find the culprit writhing in abdominal pain or worse. I should mention Barbara is a kind, loving soul, ‘but enough is enough.’
Link to the story about the leatherleaf viburnums plagued with aphids – Reasons to Prune
About Thomas Jefferson’s Monticello estate
This column is featured in Episode 29 of the Garden Dilemmas Podcast
Column updated June 6, 2021