Overwintering Shrub Roses in Minnesota

Although our Flower Carpet Ground Cover Roses from Monrovia should overwinter well, I still cover them in the fall.  After cutting the roses back to about 6 to 8 inches, I heap a  mound of dry oak leaves on them, holding the leaves in place with some sections of chicken wire and a few pavers or small logs.  Oak leaves are by far the best because they do not rot and they are easily raked way in the spring.