A handful of plants need special attention. Many roses fit this category. Some of the old roses and new roses can be very tolerant of our winters, but a lot of roses that were developed in the mid to late 1900s have a terrible hardiness record. You need to protect these to help to ensure their survival. Another plant that is in the same situation is the older blue hydrangeas.
A note on hydrangeas: Any of the white flowered hydrangeas are very tolerant of our winters, and need no special attention. The new Endless Summer blue hydrangea also will flower even after a severe winter. Any of the other blue hydrangeas need this special attention. Also hydrangeas should NOT be pruned back. Well-intentioned gardeners often do this, but it will eliminate flowering the following year. The older types flowered only on branches that grew the previous year. So if you cut the branches off, you cut the flower buds off. The older blue hydrangeas will live regardless of mulching or pruning but they will not flower, or at least not flower well.
If you have these hydrangeas or roses you will need to build a mound of mulch over them for the winter. Do this after the ground has started to freeze a little bit. This helps to keep the rodents out. It does not matter too much what you use; pine needles, leaves. Bark mulch, etc. What matters is that you make the mound large – about two feet high. Often folks will then cover it with evergreen branches for the winter. This stops the mulch from blowing away, as well as making it more attractive.
In the spring you want to remove the mulch material gradually and early. It varies greatly by year, but late March would be a good goal if it has thawed enough to start uncovering by then.
Note: Yes this is a pain in the neck. You don’t need to do this too many times before you usually decide to get one of the hardier roses or Endless Summer hydrangeas.