Answer: There are some hardy hibiscus that would survive your winters if planted in the ground and thoroughly mulched. These include the hardy shrub Hibiscus syriacus (rose of sharon) and hardy perennials such as Hibiscus moscheutos. They nauturally go dormant for the winter and then come back into growth the following spring.
However, the most common type of hibiscus grown in a container is the tropical type, Hibiscus rosa-sinensis. These must be brought indoors for the winter as they do not tolerate cold weather. They suffer cold damge when temperatures drop into the 40's. They can be kept as houseplants for the winter, or they can be stored in a cool location where temperatures stay about 45 to 55 degrees. If you try storing them, water just enough to keep the soil from drying out completely and do not fertilize while they are stored. Take them back outside in the spring when the weather moderates and resume watering and fertilizing when they start to grow again.
If your plants have been exposed to frost, they may or may not survive.
Good luck with your hibiscus!
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