Composting: Is Oleander Safe to Use as Compost in Vegetable Gardens?

I have a long hedge of pink Oleander along my driveway in South Kihei that I began pruning this weekend, after our nice rain. I’d been waiting to prune until after a rainstorm, because Oleander (Nerium oleander, a Mediterranean shrub) is highly poisonous, and dust that has settled on its leaves can irritate a gardener’s eyes and lungs. I know this from experience, as my father once pruned and chipped an Oleander hedge mid-summer and ended up in the hospital for his efforts.

Though the rain took care of my concerns about breathing posionous Oleander dust, I wondered if Oleander leaves and limbs were something that I wanted to add to the compost that I’ve been stockpiling for my backyard vegetable garden. Oleander hedges are common in South Kihei, and this seems a question that others might ask as well.

Here’s what is known:

All parts of the Oleander plant are poisonous, but especially the milky sap. It’s toxic enough that ingesting only a few leaves can kill a small child, and getting the sap on your skin can cause irritation and rash. There are anecdotal stories of people getting sick by using oleander spears for roasting foods over campfires. Even dry oleander leaves can be poisonous to pets and livestock, so never leave Oleander prunings where animals might eat them.

The good news is that the toxin in Oleander–a glycosoide called “oleandrin”–will deteriorate within about 50 days in an effective compost pile. Moreover, on tests conducted by UC Davis researchers, the toxin was not taken up by vegetables such as lettuce (which grow quickly) and tomatoes (which take longer to mature). The only possible danger the researchers noted could come from accidentally ingesting some not-fully deteriorated Oleander compost when harvesting leafy vegetables such as lettuce.

The safest solution would be to compost the Oleander leaves and twigs (taking care not to breathe the dust or getting the sap on your skin) and use them only as mulch for ornamental areas of your yard. But if you have a lot of Oleander, and want to use it for your garden, then make sure that you let it fully rot in the compost pile first, and be sure to wash your vegetables of all mulch and dirt before eating (a good practice in any case).