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.
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!
Susan Miller/ 22 Jul 2019
We have had a Rose of Sharon for several years. It is healthy and gets lots of clusters of buds. However, the buds have never opened. They eventually brown and fall off ! No one has been able to solve the problem. Any suggestions?
rgnursery/ 29 Jul 2019
Hi Susan! This is a great question. We suspect that it’s a cultural issue – i.e. the plant is not liking something about it’s site or positioning. Is it by an irrigation system or by a spout where it’s getting too much water? Is it planted too deeply? Is it heavily mulched? Have you used any fertilizer on and it and what kind? Our guess would be too much water – but let us know more and we can advise better.
Tracee/ 22 Jun 2020
It might be a Turks cap
Estonia/ 25 Jan 2020
It is often so tempting to bring tropical plants into the landscape, especially in summer. Often we need to consider these plants short-term visitors to the garden, as they will not survive plummeting temperatures. Tropical hibiscus may succumb to occasional freezes in zone 8 and should be kept in containers and moved indoors for winter or treated as annuals.
rgnursery/ 28 Jan 2020
Linda Bocchino/ 22 May 2020
I cut back my hardy hibiscus (3 separate bushes) down as I usually do in the spring but because I’m home from working at a school with theCovid situation, I cut it down a few weeks earlier than I would have but I really don’t remember when I usually see plant growth. As of this moment (May 22nd) I see NO growth. I’m hoping it may be because both April and early May were cooler than usual months here in the northeast US (outside of Rochester, NY). How will I know if it died?
rgnursery/ 25 May 2020
Hi Linda. I have great news – don’t worry. It’s still early. Those plants sleep in VERY late, and then grow like crazy once they wake up. So give it more time – even weeks really – because they really do wake up late.