Care of hibiscus plants during the winter is determined by the type of hibiscus. Tropical varieties die if left outdoors during a freeze, but perennial hibiscus plants can survive the winter with little or no extra care in some zones.
Tropical hibiscus plants must be brought indoors for the winter. They can't tolerate more than a very light freeze, or the entire plant dies. Bring the potted plants inside when the weather turns colder. Provide them with some sun and warmth until spring returns. Remember that hibiscus plants need less water in winter than in summer, so water when the soil is dry.
If a tropical hibiscus begins to lose its leaves or if it turns yellow, continue to care for it normally. It is common for the hibiscus to experience this change. If all the leaves fall off, but the branches are still alive, move it to a cool, dark place to allow the plant to go through a normal dormant period. Keep watering, but don't let the soil get overly moist.
Perennial hibiscus plants are hardy, requiring very little extra attention to survive the winter. The leaves and stems die down to the ground with colder weather, but the roots can live in freezing temperatures through zone 5 with no protection. Beyond this zone, take care to protect the roots from damaging freezes.