If winter temperatures are relatively low in the area where you live, plant the hibiscus plant in a pot, and transfer the pot inside the house before the first frost. Make sure that the temperature in the room is between 40 and 45 degrees Fahrenheit. After bringing the plant inside, stop watering it until all the leaves fall off it, and then start watering it again. Only water the plant if the soil 2 inches beneath the surface is dry.
If winters are relatively warm in your area, plant the hibiscus directly in the ground. Before winter, place some composted leaves or mulch under the plant where the roots and the stem are. Place some more mulch over the stem, layering the leaves about 4 to 6 inches thick to sufficiently protect the plant. Place some Christmas lights on the plant, and turn them on if the temperature becomes too low. To keep the heat from the light, place a tarp or frost blanket on the tree.
If you don't want the tree to become dormant, don't stop watering it when winter starts. However, the tree is not going to look as good as it does in the summer. In addition, a lot of leaves may turn yellow, which is normal. Be careful not to water the plant too much, as it may harm the roots of the tree.