I have been asking questions about winter cover for irises also, Brad. I plant my irises 'like a duck on water' with the roots and bottom of the rhizome underground. I did not lose any to the cold weather but I lost many other plants. I thought perhaps I would leave the fallen leaves on them this year but I sure do not want any to rot so maybe not. I had one that had the non smelly rot this spring and I dug it, performed drastic surgery and planted it in a pot. It came back like it was just waiting for me to rescue it. It is a favorite and hard to find. I was curious about this rot so I cut into one otherwise healthy rhizome and found a dark spot, it looked like the dark spot in a potato when it is going bad, and there was no sign of the rot on the outside. Perhaps there was a tiny opening to the surface of the rhizome but I could not see one. I am in zone 7a but that does not take into account that I am on a hill in a large valley - Ozarks/Ouachita - so I think zones within zones perhaps - but 7a is my planting zone. As I said in another thread, I have only known the ground to freeze several times in my long life here. More often when I was a kid than of late. Even then that did not hurt the established irises but I plant in June due to the early bloom season and the irises put roots down and get situated well before cold weather. I do, however, get a lot of sun burnt irises in the summer but still do not mulch due to fear of rot. I think in the future I will perhaps plant where the afternoon sun does not cook them. sigh
