Answer: It's hard to make general statements about how winter hardy plants are because there are so many gardening zones and each garden has some microclimates that might keep temperatures warmer than in other areas within the same garden. So, it will take a little homework on your part to determine whether or not winter protection is required for the plants you are growing. You are in USDA zone 5. Hardy hibiscus, clematis, butterfly bush, roses and certain hydrangeas are winter hardy in your yard; dahlias are only hardy to zone 8 and honeysuckles may or may not be hardy in zone 5, depending upon variety.
If you are growing tropical hibiscus (glossy leaves), it needs to wintered over indoors. Hardy hibiscus is quite hardy in zone 5, simply cut it back in the spring after new growth begins. Clematis is marginally hardy in zone 5. You may lose the tops in an exceptionally cold winter but the roots should be okay. You might pile a few inches of mulch over the root system to protect it during the winter months. Butterfly bush will die down to ground level but in the spring you can cut away the dead stems and branches and new shoots will emerge from the crown of th eplant. Roses can be pruned in March or April, removing winter dieback and encouraging healthy new growth. Dahlia tubers are hardy to zone 8 so after frost kills the tops of the plants you'll need to cut the foliage off at ground level and then dig and store the tubers until next spring. Some hydrangeas will die down to ground level each winter and some will survive. If your hydrangea flowers on both old and new wood, you'll have flowers each year.
Hope this answers all your questions!
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