I tried to kill it, but it just keeps on blooming now into October. I didn't water it at all. I weeded around it only twice. I staked it with something too flexible and not nearly tall enough so it fell over. But it kept growing anyway. Since it's hanging there, precariously parallel to the ground, there are shoots growing off of it in a direction that should be sideways, but instead they're straining toward the sun.
Plants that are nearly impossible to kill are right up my alley. I've heard talk that dahlias are hard. But I've had more trouble with black-eyed susans and purple cone flower. Or maybe that was because the dog was peeing on them.