Hardy Hibiscus Has Huge, Tropical-Looking Blooms But Can Take the Cold (2024)

If you picture a tropical flower, there’s a good chance hibiscus comes to mind. While tropical hibiscus is known for being easily traumatized by frost and excessive heat, hardy hibiscus (a cousin to the persnickety Hibiscus rosa-sinensis) can thrive in northern climates for years with the right care. A true showstopper, the hardy hibiscus (also known as Hibiscus moscheutos or rose mallow) is sure to impress with its vibrant, dinner plate-size blossoms and deep reddish-green to burgundy foliage.

The five-petaled blooms begin as bulging, pointed buds that unfurl into enormous discs of color that last just a day or two before being replaced with new flowers. While the majority of hardy hibiscus cultivars bloom in one solid color (typically white, pink, or red), they are often studded with a contrasting "eye" in the center of the blooms. This eye often appears in a deep red color, which makes a bold statement against some of the paler-toned petals. Some cultivars of hardy hibiscus even have light blushes on the outer edge of the petal, giving the blooms a tie-dye or swirled effect.

Where to Plant Hardy Hibiscus

Hardy hibiscus is an exciting addition to any garden space, thanks to its giant blooms. It is native to the marshes, swamps, and riverbanks of the southern and eastern United States, so it grows easily in moist to wet soils with exposure to lots of sunlight. In cooler climates, choose the sunniest location to plant your hibiscus. In warmer climates, it may be best to choose a spot with shelter from the harshest afternoon sun.

Once established, hardy hibiscus plants grow quickly, adding a colorful touch to cottage gardens, coastal gardens, and perennial borders. They also make fantastic foundation plantings along the side of a structure or when used as a flowering hedge.

Because these plants can reach up to 7 or 8 feet in height, they can create quite a statement in a garden, even when not in full bloom. Plant hardy hibiscus at the back of the border so they don’t block any of their smaller companions, then sit back and wait for the fantastic flowers to begin.

How and When to Plant Hardy Hibiscus

If you are growing hardy hibiscus from seeds, you should start them inside approximately 12 weeks before the last frost and plan to transplant them after the danger of frost has passed in the spring. You can plant nursery-grown hardy hibiscus or transplant dormant hardy hibiscus in the spring or early fall.

To plant seedlings or established plants, dig a hole twice the size of the plant’s current pot and place the plant in the center so that the root crown sits just at or slightly above the surface of the soil. Hold the plant steady and add the soil back, tamping it down gently as you work. Water thoroughly.

If you are planting multiple plants or creating a flowering hedge, be sure to allow at least 2 to 3 feet of space between plants as they will not grow as well if crowded too close together.

Hardy Hibiscus Care Tips

Compared to their tropical relatives, hardy hibiscus plants are astonishingly easy to care for when grown in the right conditions. Once established, these large-scale herbaceous plants are quick to grow and fill a space each season—although they may take their time emerging in the spring.

Light

Hardy hibiscus plants require at least 6 hours of full sun each day to bloom prolifically. The burgundy leaf varieties will also produce more vibrantly colored foliage when placed in an area with full-sun exposure. In cooler climates, this could mean planting your hardy hibiscus in a south-facing garden spot to maximize exposure.

If you live in a particularly hot climate, consider placing your hardy hibiscus in an area where it will be protected from the harshest afternoon sunlight—like the east-facing side of your house.

Soil and Water

Hardy hibiscus plants prefer organically rich, consistently moist to wet soil with a slightly acidic pH of 6.0 to 6.5. They will, however, tolerate a soil pH of 5.5 to 7.5.

Hardy hibiscus plants do not like to dry out too much. In fact, they can take quite a bit of water and can grow in marshy conditions as well. If your region does not have natural rainfall throughout the growing season, supplement by watering deeply two or three times per week—especially during the first growing season.

Temperature and Humidity

Like its tropical cousin, hardy hibiscus thrives in temperatures between 60- and 85 degrees Fahrenheit and mid to high levels of humidity. Unlike tropical hibiscus, hardy hibiscus can tolerate much cooler temperatures and will survive a frosty winter without much assistance.

In the winter, your hibiscus plant will die back to the ground and enter dormancy. This is normal and allows the roots to withstand the winter chill.

Fertilizer

Hardy hibiscus will benefit from regular feeding—especially if you want yours to continue blooming all summer long. The best time to fertilize your hardy hibiscus is in the spring after new growth emerges. Feed it with a balanced water-soluble plant food or sprinkle a slow-release fertilizer around the roots (avoid the stem and foliage) three times across the growing season.

Pruning

Hardy hibiscus plants do not require much pruning, but deadheading the spent blooms can help promote flowering.

In the winter, when your hardy hibiscus dies back, trim the dead stems back to just a few inches above the ground to prevent new growth. This will help your hibiscus enter dormancy and protect its root system through the winter months. If your winters are particularly cold, add a thick layer of mulch (about 8 inches of bark, straw, or shredded leaves) to insulate the roots.

Potting and Repotting

Hardy hibiscus can be grown in containers, but it is best kept outdoors because the humidity levels indoors are often too dry to keep hibiscus plants happy. If you would like to grow hardy hibiscus in a container, choose one with drainage holes that will accommodate several years of growth without transplanting (at least 8 inches depending on the size of your initial plant). Prepare your new container by filling it partway with a high-quality potting mix. Set the plant in the container so the crown of the plant or the top of the root ball sits at least 1 inch below the top of the container. Fill in the rest of the soil and gently tamp it down to remove the air pockets. Water the plant thoroughly until the excess water drains from the container and add more soil if the plant settles.

Hardy hibiscus can also suffer shock from excess root disturbance, so avoid transplanting yours unless necessary. If you must move yours to a new container, do so in mid spring after new growth emerges. Water the plant thoroughly for at least 1 to 2 days before the move and prepare the new pot. When you are ready, dig a trench around the edge of the plant at least 12 to 14 inches from the stem using caution not to dig into the roots. Dig the trench outward from the stem and down until you can lift the root ball. Place the plant in its new container with the crown at the same level as it was in its previous pot. Fill in half the soil, water well, and top with the remaining soil as you tamp it down to remove air pockets. Add a layer of mulch and water the plant every few days for 4 to 6 weeks.

Pests and Problems

Like many bold garden blooms, hardy hibiscus plants can suffer damage to their leaves and flowers from aphids, scale, spider mites, Japanese beetles, thrips, and whiteflies. Most of these can be deterred with the use of insecticidal soap or neem oil.

Hardy hibiscus may also be prone to above-ground fungal diseases like rust, botrytis blight, and leaf spot as well as root rot. To avoid these issues, place your hardy hibiscus plants at least 2 to 3 feet apart so they have ample air circulation and avoid watering overhead.

How to Propagate Hardy Hibiscus

Propagating via Seeds

Collect the seedpods by snipping them from the plants just as they begin to crack but before they fall. Remove the seeds from the pods and store them in a dim, dry place until it is time to start the seeds indoors. Approximately 12 weeks before the last frost, soak the seeds overnight and sow them into grow pots filled with a soilless potting mix or a combination of equal parts sphagnum peat moss, vermiculite, and compost. Cover the seeds just slightly and place them in a warm, sunny area. Keep the growing medium moist until the seeds start to germinate. Once the seeds have begun to sprout, place the grow pots in a window with full to partial sunlight and keep the mix evenly moist for several more weeks until the danger of frost has passed, and you can plant the seedlings outside.

Propagating via Cuttings

Cuttings can be taken from healthy hardy hibiscus plants in the spring or early summer as new growth emerges. Choose a 4 to 6-inch section of softwood growth and cut it just below a leaf node using sharp garden shears. Remove any leaves from the bottom portion of the cutting, dip the cut tip in rooting hormone, and stick it into a 50/50 mix of potting soil and perlite that has been thoroughly watered. Wrap the entire pot in a plastic bag and place it in an area with partial shade to take root. Keep the soil evenly moist, but not wet for approximately 8 weeks. Once the plant is rooted, it can be transplanted into a larger pot.

Types of Hardy Hibiscus

People are always wanting more of these tropical-looking hardy plants. Luckily, breeders are constantly improving hardy hibiscus and adding more colors to the palette. Almost every year, they release new varieties with darker foliage colors, new floral patterns, higher bud counts, and better branching.

'Blue River II' Hibiscus

Hibiscus moscheutos 'Blue River II' shows off 10-inch-wide, pure-white hibiscus blooms on 6-foot stems in midsummer to fall. It is hardy in Zones 5-10.

'Fireball' Hibiscus

Hibiscus moscheutos 'Fireball' is one of the most stunning perennial hibiscus plants. It bears bold red flowers up to 12 inches across on 5-foot-tall stems. It grows 3 feet wide in Zones 5-9.

Hibiscus makinoi

Hibiscus makinoi shows off large pink flowers that span up to 5 inches wide. This hibiscus plant bears fuzzy green foliage and can grow 7 feet tall and 5 feet wide in Zones 7-10.

'Lord Baltimore' Hibiscus

Hibiscus moscheutos 'Lord Baltimore' bears 10-inch-wide, bright cherry-red flowers on 4-foot stems in midsummer to fall. It is hardy in Zones 5-10.

'Luna Pink Swirl' Hibiscus

Hibiscus 'Luna Pink Swirl' is a compact selection bearing 8-inch-wide flowers in pink and white. This hibiscus plant grows just 3 feet tall and wide in Zones 5-10.

'Luna Red' Hibiscus

Hibiscus 'Luna Red' is another compact selection at just 2 to 3 feet tall. Its 8-inch, deep burgundy flowers bloom from midsummer to fall in Zones 5-10.

White Rose Mallow

Hibiscus coccineus albus is a Texas native that offers pure white flowers from summer to fall. This hibiscus plant loves moist soil and grows 10 feet tall and 4 feet wide in Zones 6-11.

'Strawberry Swirl' Hibiscus

Hibiscus moscheutos 'Strawberry Swirl' offers creamy-pink and white flowers with red centers and maple-shape foliage. This hibiscus plant grows 4 feet tall and wide in Zones 4-10.

Companion Plants for Hardy Hibiscus

Joe Pye Weed

Joe Pye weed is a showstopper of a prairie native, producing huge, puffy flower heads in late summer. Like hardy hibiscus, it prefers moist soil, but thanks to its extensive root system, it also tolerates drought well. It is a large plant, growing 4 to 6 feet tall. Closely related, hardy ageratum is a spreading plant that grows to only 2 feet tall. Another relative, white snakeroot, reaches 4 to 5 feet tall. All are great for naturalistic or cottage plantings and for attracting butterflies.

Miscanthus

Miscanthus is one of the most prized ornamental grasses, and one particular cultivar, 'Morning Light', sums up much of its appeal: This grass is stunning when backlit by the sun, either rising or setting. Statuesque miscanthus makes dense clumps of arching grassy foliage in an assortment of widths, decoration, and fineness, according to variety. Dramatic erect plumes of flower spikelets rise among the leaves or well above them and last beautifully through the winter. Site miscanthus with good drainage and plenty of space in sun or light shade.

Turtlehead

This native perennial gets its name from the shape of its unusual flowers, which resemble the heads of snapping turtles. It spreads to form dense colonies of upright stems bearing pink, rose, or white flowers from late summer into fall. It grows best in some shade, and is a good choice for heavy, wet soils. It tolerates full sun with adequate moisture.