In the Garden with Pat Rubin

Bee garden writer Pat Rubin writes about everything that grows, from flowers and trees to vegetables and lawns. Pat volunteered for several years as a Placer County Master Gardener and has written about gardening for many national and regional publications. In addition to gardening, she spends time raising and showing miniature horses and miniature donkeys.

In the Garden will include news, events, advice and other gardening tidbits. Pat will also answer reader questions.

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January 25, 2008

Oleander toxins

Q: I’m replacing a 20-year-old oleander with a lemon tree. I’ve heard oleanders are toxic. Will this affect the lemons?
Ednajo Hegseth, Sacramento

A: Oleanders are tough, drought tolerant plants that grow, even thrive, along freeways as well as in yards. And you’re right, they’re poisonous. In fact, all parts of the plant are toxic if ingested, and even inhaling the smoke from burning them can be harmful.

According to the International Oleander Society, the plants contain a toxin called cardenolide glycosides. “The toxin is mostly contained in the sap which is clear to slightly milky colored, and sticky. When ingested in certain quantities, this toxin can cause harm - and possibly death. The extremely bitter and nauseating taste of the sap (much like a rotten lemon) causes a mechanical reflex in the stomach which rejects and expels the vile substance,” says the International Oleander Society’s website. Wikipedia also has some useful and interesting information about oleanders.

Try to remove all parts of the plant: branches, leaves, debris, and roots. Wear gloves when handling the plant, and wash your hands thoroughly afterwards.

The good news is these toxins do not somehow become part of the soil, and plants do not “take up” toxins simply by growing near a poisonous plant or where one was previously planted.

Juliet Voigtlander, owner of El Dorado Nursery, suggests digging a hole twice as wide as the container and the depth of the root ball” for your new lemon tree. “Wide and shallow holes are best, and amend with compost. Be sure the tree sits above grade when planted. Citrus thrives in full sun with little water and good drainage,” she says.

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