If you crave a taste of the tropics in your northern climate, try your hand at growing a hardy hibiscus plant. Native to North America, they produce oversized flowers (often the size of a dinner plate), add color to your summer garden, and attract hummingbirds and butterflies. While each bloom lasts only a day or two, they are quickly replaced by new blooms.
Click Play to Learn How to Grow Hibiscus Plants Outdoors
Hardy hibiscus can be planted in spring when there is no risk of frost. The plants will grow quickly, erupting each summer with huge, showy flowers that feature tissue-thin, ruffled petals in shades of pink, red, magenta, and white. Some varietals produce blooms with dark-colored centers. You might be tempted to cut a bouquet, but don't—hibiscus blooms are better-suited in the landscape than being cut and placed in a vase, where they'll last only a day or so.
|Botanical Name||Hibiscus moscheutos|
|Common Name||Hardy hibiscus, rose mallow, swamp mallow|
|Plant Type||Herbaceous perennial|
|Mature Size||3–7 ft. tall, 2–4 ft. wide|
|Sun Exposure||Full sun|
|Soil Type||Average, organically rich|
|Soil pH||Neutral to acidic|
|Soil Moisture||Moist to wet|
|Flower Color||White, red, pink, blue|
|Hardiness Zones||5–9 (USDA)|
|Native Area||North America (Missouri)|
Hardy Hibiscus Care
Hardy hibiscus plants are cold-hardy despite bearing large blooms that look at home in the tropics. Although the plants seem woody in summer and function as sub-shrubs in the landscape, their stems die back to the ground in winter, technically classifying them as herbaceous perennials.
Hardy hibiscus plants are surprisingly easy to care for considering their bountiful, delicate blooms—if they receive enough sunlight and water. They do well as container-grown plants, too, allowing you the opportunity to bring the plant indoors for the winter season if you live in a cold climate. Repot container-grown hibiscus into a larger pot every two to three years.
For your hardy hibiscus plant to bloom to its greatest potential, it needs at least six hours a day of full sun. However, if you live in a hot and dry climate, provide your hardy hibiscus occasional relief from the hot afternoon sun—grow other leafy plants nearby to cast a shadow or choose a planting location that is lightly shaded in the afternoon. Indoor hibiscus plants should be situated near a sunny (preferably southwest facing) window—if that doesn't provide your hibiscus with enough light, you can augment with grow lights.
Hardy hibiscus are wetland plants, and therefore are the ideal specimens for moist areas on your property where it might be difficult to grow other plants that don't require as much moisture. Hardy hibiscus also grow well when planted around water features and ponds. Hardy hibiscus plants require organically rich soils—if the soil in your landscape is not rich with organic material, amend the planting area with organic compost before planting.
If you can't locate hardy hibiscus plants in a moist spot in your landscape, make sure to keep the plants adequately watered—but don't overdo it. A small plant with fewer leaves needs less water than a large, leafy plant. In warm weather, you'll need to water your hibiscus plant daily; In the winter, water it only when the soil is dry to the touch.
Temperature and Humidity
Hibiscus plants flower best in temperatures that range from 65 degrees Fahrenheit to 75 degrees Fahrenheit. Bring plants indoors before temperatures dip to 32 degrees Fahrenheit, but be mindful that low humidity can dry them out quickly. If you bring your hardy hibiscus indoors for the winter, you'll need to mist the leaves daily or place each pot on a pebble tray filled with water. As the water evaporates, the humidity will rise around the plant. A small space humidifier will also raise humidity levels in your home.
Hardy hibiscus plants need plenty of nutrients and regular feeding. Feed your plant with a diluted liquid fertilizer once a week or a slow-release fertilizer three times a year: early spring, after the first round of blooming; and mid-summer.
Hardy Hibiscus Varieties
Some of the most common hardy hibiscus vary in size and blooms:
- Hibiscus moscheutos 'Lady Baltimore': This varietal is four to five feet tall and up to three feet wide. It features light pink flowers with a dark pink center.
- Hibiscus moscheutos 'Robert Fleming': This compact varietal is about two to three feet tall and wide at maturity. Its huge blooms are a deep, velvety red.
- Hibiscus moscheutos 'Summerific® Perfect Storm': This compact and well-branched varietal produces dark purple foliage and can grow to be five feet tall and five feet wide. Its large seven-inch whitish-pink flowers have a red eye.
Pruning Hardy Hibiscus
Because this plant dies to the ground in winter, you can prune it down to the ground in fall or in spring before new growth emerges. The root system will survive the winter, and new growth will emerge from the root system.
Propagating Hardy Hibiscus
The best way to propagate hardy hibiscus is through stem cuttings. In spring or early summer, cut a section of new growth or softwood about 3 to 5 inches long, removing any flowers or flower buds from the node area. Pour some rooting hormone into a shallow dish, moisten the cut end of the stem, and dip it in the powder. Use your finger to create a hole in the moist growing medium, ensuring the hole is wide enough so that the rooting hormone won't rub off when you place the cutting into the hole. Tamp down the soil around the cutting and water well.
Cover the cutting with a plastic bag, and place it in a warm location with temperatures of 60 degrees Fahrenheit or higher. New leaves should appear eight weeks later; when the cutting has developed a root system, repot it into a larger pot.
Common Pests and Diseases
Hardy hibiscus plants have a tendency to be bothered by various fungal diseases such as leaf spot, blight, and rust, which often develop when the plant is subject to excessively moist conditions. To avoid such problems, when you water your plant, apply the water to the base of the plant so you don't introduce excess moisture onto the foliage. Proper spacing between your hardy hibiscus and other plants is key as well—adequate airflow will help prevent the development of fungal diseases. If all else fails, you can periodically treat affected plants with a fungicide.