Do you have outdoor (not LED) christmas lights? If so string them thru your iris and plug them in for the evening. Yes, the neighbors will talk. ;-) You can also throw a cotton or plastic sheet over them to keep the frost from settling on the iris. If plastic be sure to get out first thing in the morning and remove it so the iris don't cook. Sheets should not touch the plants so stake them up.

Riley uses socks.
Renee

Thank you both for your response's. Unfortunately the frost was that very same night. The scapes seem not to have been damaged by the frost, and their buds are begining to swell, so I am keeping my fingured crossed that they will open fully. I thought that night of covering each clump with an oversized flower pot or bucket and placing a quilt over that. It never occurred to me to use Christmas lights...and I have no idea how I would go about using socks. Lol. However I will have to remember these tips when they bloom again in autumn. Many thanks for your valued time.