Wait, you've only gotten a flower once? I'll send you some of mine if you want to see if it's dependent on the particular plant. My adelae seem to grow two stalks a year around this time, and they keep blooming down the spike until early December. I also saw the same thing with the flowers never falling off. I pulled the old spikes off today because they were looking bad with the new ones, but I think they would have stayed on until they rotted away if I hadn't.