Plants in general? How haven't I killed them? That would be a much shorter list. Let's see...Round-up "drift", on purpose, accidentally, over and under watering, not enough light, too much light, wrong soil, improper placement, backing the car over them, neglect(benign & otherwise), the opposite of neglect, resentment(in the case of the Darlingtonia), evil thoughts, evil intentions, the "glove of death", and drunken gardening.