Q. I read you said recently that oleanders can be composted. Just for clarification, can they be composted for vegetable gardens since they are toxic?
A. Yes! They can be used for mulching and composting! Mulching is when the plant is chopped up into small pieces and laid on the soil surface. Composting is the controlled rotting of the plant so that it can be mixed in the soil as an amendment and fertilizer.
There is contradictory information circulating on the Internet about the safety of oleander but the study below strongly suggests that there is no problem with it when it is composted and used for growing vegetables. They do warn that it is not safe to eat the compost (why someone or an animal would do that I don't know). It is also not a problem to compost eucalyptus as well.
The smoke when burning oleander is a problem if inhaled. Although about 60% of our landscape plants are poisonous to some degree, oleander is one of the most toxic along with Datura spp. (a.k.a. Jimson Weed, Angel’s Trumpet, Thorn Apple), Nightshade, Castor Bean (Rosary Bead), Rhubarb, Moonseed, Lantana, Yew and Wisteria.