I was wondering what others do for their rhodies over winter if their winters get down to -20 every so often. I wrap mine in a cage, then burlap, then fill with leaves. They stay nicely green all winter when thus protected from sun and wind. Cold doesn't matter apparently.
"They" were just talking about that here: http://davesgarden.com/community/forums/t/1204483/
I also wrap my two 3-foot tall rhodies in burlap to keep the leaves and buds from wind damage. I have a very small Patty Bee rhodie that I just put a layer of leaves on top, no burlap.
Cold does matter if you go below the low temperature a plant can stand. You are in a very cold zone and must have varieties that are hardy to that temperature. You are doing the best treatment for Winter protection however.
After a mild Winter ( For me), and a very warm early Spring, It turned bitter cold last night( 25F) and all the small leaf rhodies that were in bloom were frosted. There are still many more to come however and the ones that were frosted at least showed their bloom for a week or 2, mostly Mucronulatum and its hybrids. The weather is warmer again and still more bloom is in store for me. Still to bloom are the following lepidote hybrids: Lems Augustii, Guy Nearings Little Guy A dwarf Guyencourt , 2' in 25 years, Wind beam,
Wyanokie, Dora Amateis, Mary Fleming,etc.
Mine are still hiding under 2' of snow in their 'winter robes.' Always interesting to see how successful they are.