"The surest way to get roses to survive winter in northern Michigan is to bury them in a trench. Dig a trench right next to the main stem, large enough to accommodate the branches when they are tied up into a bundle. Tip the plant over into the trench, pinning down with wires if necessary, and bury with soil. (Do this after temperatures have gotten down into the low 20's several times.) Mulch over the soil with shredded leaves.
Alternatively, you can mound soil up around the stems, and mulch heavily. Using this method, the roses will likely die back to the mulch line. Piling snow on as additional mulch also help protect the plant.
Avoid pruning the roses severely this fall. That decreases their winter hardiness."