Do you love the look of tropical hibiscus but hate having to toss the plant on the compost pile at the end of the growing season or watch all its leaves fall off when you try to overwinter it indoors? What if I told you there was a way you could enjoy those same big, gorgeous blooms without needing to worry about what to do when cold temperatures arrive? Say hello to the hardy hibiscus! Yes, you heard me right. Let me tell you more about this amazing perennial hibiscus.
What is a hardy hibiscus?
These herbaceous perennials are hybrids of a few different North American native Hibiscus species. One of the most common parents, species Hibiscus moscheutos, is a perennial hibiscus that grows in the wet soils of floodplains, marshes, and meadows. Because of this, it’s also known as the swamp mallow or the rose mallow. Depending on the variety, other parents could be Hibiscus syriacus, H. coccineus, H. palustris, and several others. Breeders recognized the merits of these plants decades ago and began to hybridize for increased bloom size and different color forms. Now, there are dozens of cultivars on the market with blooms ranging from burgundy and pink to white and bicolor. During the hybridization process, the need for damp soils was also diminished.
The hardy hibiscus plant
A single hardy hibiscus plant can produce dozens of show-stopping blooms that measure up to 10 inches across. Each flower only lasts a day or two, but when one flower dies, another bud opens for a long succession of blooms. My first experience with a hardy hibiscus was while working at a public park in Pennsylvania just after earning my horticulture degree. I was stunned when an unassuming shrub-like plant burst into bloom in mid-summer and continued blooming through September. The plant in that park produced dark wine-colored blooms, and for me, it was love at first sight. I’ve had one in my garden ever since. In my current garden, I have three of these beauties.
Though the tropical-looking flowers are this plant’s main draw, the foliage is also quite lovely. Some varieties have deep green rounded leaves with slightly serrated edges, while others produce deeply cut, maple-like leaves. I even have one with burgundy foliage. Depending on the variety, hardy hibiscus plants can grow between 3 and 6 feet tall.
Each plant produces multiple, upright stems that grow from the base of the plant each spring. They are not evergreen plants, but rather they die back to the ground each winter. The clumps increase in size each year, leading to more and more blooms over time, though do be forewarned that the plants are fairly late to emerge in the spring. Mine sometimes don’t sprout from the ground until mid-May. They are sturdy plants that need little in terms of nutrients or fertilizer.
Perennial hibiscus flowers
Also known as a dinner plate hibiscus, each individual flower is between 4 and 10 inches across, depending on the variety. The blooms have five papery petals with a central protruding stamen that is sometimes surrounded by a dark “eye” at the center of the bloom. They come in shades of pink, white, burgundy, and red.
Each stem produces multiple buds, most often at the top of the stem. If you want to stagger the bloom time and keep the plant stems more compact, pinch back every other stem (or all the stems if you want) by half the plant’s height in early summer, just like you would do with phlox or mums. The hummingbirds, bees, and butterflies enjoy the blooms, too.
How hardy is a perennial hibiscus?
Hardy hibiscus is fully hardy in USDA zones 5-9 which means the plants survive winter temperatures as low as -20°F. It shrugs frost off like a champ. Since it dies back to the ground each winter, there is no need to mulch the stems through the colder months. Though it looks tropical and fragile, hardy hibiscuses are tough plants that don’t require coddling.
Where to grow perennial hibiscus plants
With at least one of its parents being native to low-lying, damp soils, hardy hibiscus is a great fit for poorly drained areas. However, it also thrives in average garden soil. Amend the soil with compost prior to planting and keep the plants well-watered during times of drought. Mine are growing in my perennial beds without any extra fuss.Yes, the flowers do look a bit like the blooms of rose of Sharon, but this is a different plant species.
Select a site that receives full sun. Shadier conditions result in too-tall stems that flop under the weight of the flowers. A minimum of 6 hours of full sun per day works, but 8 or more hours is ideal. If the plants sprawl due to lower light levels, consider using a peony ring or grow-thru plant support to keep them upright. Some varieties are more upright and rigid while others are more rounded in form. Be sure to consider where they’ll be planted when choosing a variety to add to your garden.
Hardy hibiscus pests
Though this tropical-looking perennial is easy to grow, it does have two pests that can become quite bothersome. Here’s how to tackle them if they are an issue in your garden.
- Japanese beetles: If these shiny beetles begin to feed on the foliage of your dinnerplate hibiscus in summer, handpick them and drop them into a container of soapy water, or use a spray product with the organic insecticide Spinosad (Captain Jack’s Deadbug Brew is one of my favorites). Don’t spray when pollinators are active and follow label instructions carefully.
- Hibiscus sawfly larvae: These tiny green caterpillars are found on the undersides of the leaves in early summer through fall. They quickly skeletonize the leaves, rendering the plant very unsightly. Thankfully, they are easily managed with horticultural oil (be sure to get it on the undersides of the leaves), Spinosad (see above), or insecticidal soap.
- Aphids and whiteflies: These two sap-sucking pests can occasionally be problematic, but they are easy to keep in check by encouraging beneficial predatory insects like ladybugs and lacewings.
Hardy hibiscus varieties
There are many different varieties of perennial hibiscus, each one with its own merits. Here are some of my favorites:
- The ‘Disco Belle’ series: This series includes selections such as ‘Disco Belle Pink’, ‘Southern Belle,’ and ‘Dixie Belle’ among others. They come in a range of colors.
- ‘Lady Baltimore’ and ‘Lord Baltimore’: Two very popular selections that produce many flower buds per plant.
- ‘Brandy Punch’: A bright pink selection with a deep red eye and red-tinged stems.
- The ‘Luna’ series: This series includes selections with white flowers, red flowers, and pink flowers.
- ‘Midnight Marvel’: The lovely, burgundy-tinged foliage makes a great backdrop for the huge, deep red blooms.
- ‘Kopper King’: Produces huge, bi-color blooms that measure a foot across. The foliage is copper-colored and highly serrated.
I hope you’ll find a place in your garden for the hardy hibiscus. These resilient plants are powerful bloomers that provide a kick of color to the summer garden. They’re a great way to bring a touch of the tropics to a temperate garden.
For more on growing beautiful flowers, please visit the following articles:
- Purple-flowering perennials
- When to cut back irises
- Shasta daisies
- Pink perennials
- Blue hosta varieties