Hibiscus in Winter
This year I bought two hibiscus plants that I adore. I planted them in the ground, so bringing them inside for the winter would be impractical. Any hope that I could treat them the way I do my banana plants every year? --- I cut them down near the ground and cover with a huge pile of mulch. A sheet of plastic is secured on top. Plastic and most of mulch are removed in the spring. Lots of new growth comes to life. It rarely gets below 18 degrees here in downtown DC.
Tropical Hibiscus would not survive a winter that had more then a couple days of temperatures below 35 degrees.
Here is a link with more information.