Hibiscus plants (Hibiscus spp.) come in two main varieties. The dependable hardy hibiscus types naturally go dormant in winter and the roots withstand winter cold. Tropical hibiscus are often treated as annuals because they require special care to survive even mild winter cold. Protecting both varieties and ensuring a proper winter dormancy period gives the plants time to rest so they can produce healthy new growth for the following summer.
Hardy hibiscus varieties require minimal care to remain dormant through winter. The plants naturally enter dormancy during the fall in U.S. Department of Agriculture hardiness zones 4 through 9. The leaves turn brown after the first frost and the plant appears dead. Trimming the dead stems back to the ground prevents new growth during brief periods of warmer winter weather. A winter mulch applied over the roots, 8 inches deep, insulates the roots of the plant against cold and prevents early new growth until spring or early summer. Use chopped leaves or pine straw for the mulch.
Potted Tropical Hibiscus
Tropical hibiscus plants are only perennial in USDA hardiness zones 10 and 11 unless you protect them during winter dormancy. Growing the plants in containers makes it easier to protect the plants from cooler temperatures. Bring the plants indoors once temperatures begin to drop below 50 degrees Fahrenheit at night. Reduce watering and only provide the plants with bright indirect light so the leaves yellow and fall off naturally, which forces the plant into dormancy.
Garden-Grown Tropical Hibiscus
Garden-grown tropical hibiscus is more difficult to bring indoors. Dig up the plant before temperatures drop below 50 F and plant it in a pot large enough to contain the root system. When digging, avoid cutting the roots and slide the shovel beneath the roots to lift it out of the ground to minimize breakage. Bring the potted hibiscus indoors and begin forcing it into dormancy as you would a container-grown plant.
Tropical Hibiscus Dormant Care
Keep tropical hibiscus in a cool, dark location where the temperature remains near 50 F, such as an unheated garage or a basement. Warmth and sunlight may make the hibiscus break dormancy too early. Tropical hibiscus do not go completely dormant so the plants do require light watering through winter. Supply only enough moisture so the soil doesn't dry completely. Gradually increase watering and expose the plant to increased levels of sun and warmth in April so the hibiscus can begin breaking dormancy and putting on new growth.
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