Hibiscus for Northern Gardeners: Tropical, Perennial, and Rose of Sharon

Hibiscus are confusing. Especially in the North. Are they shrubs? Are they for containers? Will they survive in the cold? How do I know which to get? They all look similar but are very different plants. So let’s take a closer look at the three most common hibiscus plants found in New England gardens.

Tropical Hibiscus
When people think of a traditional hibiscus bloom, they most often picture a Tropical Hibiscus. Big, bright blooms with a bold-colored “throat” and a very long stamen. The Latin name for Tropical Hibiscus is Hibiscus rosa-sinensis. The plant features evergreen foliage and large, showy flowers that bloom from summer through fall. The plant is only hardy in zones 10 through 11 (New Hampshire is a Zone 5-6 for the most part), so it’s usually grown as a potted annual by Northern gardeners. In pots, it will reach about 3 feet tall and wide. Place a potted Tropical Hibiscus in all-day sun and keep the soil evenly moist and well drained to prevent water stress. It will not tolerate temperatures below 50 degrees Fahrenheit so bring the potted hibiscus indoors if temperatures drop below that. You can overwinter these plants with some care and attention. Bring them inside to a warm and sunny location, and keep the soil as evenly moist as you can. Check for bugs. Leaves will drop off, and it may look a little haggard, but it will spring back once placed outdoors in warm weather again. Loved by pollinators.

Hardy, Perennial, “Dinnerplate” Hibiscus
Hardy hibiscus are most often known for their HUGE, multicolored blooms, which can reach 10-12 inches in diameter — the size of a large dinnerplate — and thus its nickname. Their Latin name is Hibiscus moscheutos. They are medium- to large-sized, bushy perennials that are winter-hardy as far north as Zone 4. They are slow to emerge in spring or early summer, so be patient. Once they’ve awakened, they will grow 3-8 feet tall, and 5 feet wide. Hardy Hibiscus are heavy feeders that do best in rich, well-drained soil, and in full sun. They will survive in partial shade, but flowering will suffer. If you live in areas with very hot summers, these Hibiscus may need some mid-day shade. Like daylilies, individual flowers last for one day, so deadhead spent, mushy blooms in the evenings to keep the plant looking its best. Pruning before flowering will create a bushier plant and not sacrifice any blooms. Fertilize them in the spring, and prune last year’s stems to about 5 inches of stem. Watch out for Japanese Beetles. Because of their height, Hardy Hibiscus should be planted in the back of perennial flower beds, or as a stand-alone specimen plant. Loved by pollinators.

Rose of Sharon
Like the Hardy Hibiscus, a Rose of Sharon offers a lot of value because of its relatively late period of blooming, when many other shrubs have ceased blooming for the year (in the Northeast, Rose of Sharon starts blooming in August). It is nicknamed the “Nantucket Hedge,” and is sometimes called an Althea as well. Like other types of hibiscus, its flowers can be multi-colored and bear a striking central “throat” and long stamen. Rose of Sharon is a large, upright, vase-shaped, deciduous shrub (some say tree) that can grow 8-10 feet tall. It is  hardy in zones 5-9. It likes hot, full sun to partial shade, and is extremely low maintenance. Prune right after flowering if you want to control its size and shape, although many gardeners let them grow unattended. The plant thrives in moist, well-drained soil, and is very tolerant of air pollution, heat, humidity, poor soil, and drought. Watch for Japanese Beetles. Contrary to its name, the plant is not really a rose at all. Nor is it native to Syria, as is suggested in its Latin species name Hibiscus syriacus. This plant’s origins hail from India, China, and Korea, and has become a perennial favorite of New England gardeners. It makes an excellent hedge or specimen plant. Loved by pollinators.

In Store Now
So those are the three best hibiscus choices for Northern gardeners! We hopes this demystifies them somewhat, and lets you choose the plant that’s right for you. Right now, in July, we are only carrying the Hardy Hibiscus and Rose of Sharon, but we always carry Tropical Hibiscus in the spring and very early summer. All of these hibiscus come in a wonderful variety of colors and bloom types. Swing on by to see the varieties, and we hope you enjoy!