My great grandfather lost several cows to oleander in California in the late 1800s. We sould never plant them on our property. In fact a lot of Californians call oleanders “freeway flowers” because the state landscapes the freeways with oleander bushes because they don’t require much water.
Had em in FL they don’t require much of anything other than Loppers
I’ve gotten rid of most of the ones around my house. They’re difficult to kill once established. They were very popular when my house was built back in the ‘80’s so I had a bunch in the backyard. I’ve always hated them because they are so prolific, even if you don’t bother watering them.