Frost damage will cause the crinkled growth, and clumped leaves. Yours is really excessive though. Since it has happened more than once I wonder if your iris has a mutation.
"The chimera is a one time happenstance event where the plant has a senior moment and forgets what it is doing." - Paul Black
Rob, your iris are showing signs of loneliness, It means that they are lonely and you need to order a bunch of new ones pronto before they die of a broken heart. Yah, Really!
Politicians are like diapers, they need to be changed often, and for the same reason.
Charlotte, mine was actually a mutation. I ended up digging it up and pitching it after 3 years of the same thing. I thought it was a chemical issue at first but it turned out not to be.
