In zone 6, my knockout roses have several dying branches. This Winter was very cold. How do I protect the roses in winter?
How to Protect Roses in Winter
Knockout roses are no different that other roses in protecting them for the winter. The object is to keep them cold once the weather has turned cold so that they do not get any ideas of strong growth leading to blooming at the wrong time of year. Here is a link to an article on this subject for you: https://www.gardeningknowhow.com/ornamental/flowers/roses/mounding-roses.htm
And this article too: https://www.gardeningknowhow.com/ornamental/flowers/roses/roses-winter-care.htm