Essential Hibiscus Care Guide

There are three popular categories of hibiscus. The most familiar is tropical hibiscus, found in your local garden center each spring. There are two more types to look for in gardens and garden centers. You may be familiar with shrub hibiscus, also known as Rose of Sharon, and hardy hibiscus, known as rose mallow.

Tropical hibiscus shrubs are native to warm parts of Asia and tropical Pacific islands. In the U.S., they’re hardy in zones 10 to 12, meaning they’re not frost tolerant. Outside of these warm zones, you can grow hibiscus as annuals or overwinter them indoors. You can sometimes find tropical hibiscus with braided stems grown as small trees.

Shrub hibiscus plants are often called by the old-fashioned name Rose of Sharon. Like tropical hibiscus, they’re native to southern and central Asia. Shrub hibiscus plants are more frost tolerant than tropical varieties. In the U.S., shrub hibiscus is usually hardy in zones 5 to 9. Because they’re so hardy, some shrub hibiscus varieties can grow to heights up to 15 feet.

Hardy hibiscus species are native to North America. Hardy hibiscus are sometimes called rose mallow or perennial hibiscus. They grow in hardiness zones 4 to 9, and unlike shrub hibiscus, hardy hibiscus will die back to the ground each winter and emerge again in spring. When shopping for hardy hibiscus, look for cultivars of these plants with bloom colors including pink, white, red and yellow.

Tip: When purchasing shrub hibiscus plants, look on the product information or tag for mature size and plant in an area that will suit the plant. If you’re a small space gardener, look for newer cultivars that are “patio sized.”

All hibiscus are full sun plants. This means they need at least six hours of sunlight each day. They may be okay in less light, but keep in mind that less light means fewer flowers. Some hardy hibiscus have darker leaves; less light means the foliage will not be as dark as it would be in full sun.

If you live in zones 10 to 12, you can plant tropical hibiscus in the ground, and it will continue looking lovely throughout the year. For all other zones, tropical hibiscus is grown in containers.

You can grow all kinds of hibiscus in planters, but shrub hibiscus will likely outgrow the pot within a few years.

Keep these tips in mind for growing all hibiscus types in planters.

• Select a container that is one to two inches larger than the root ball. Hibiscus like to have crowded roots.
• You can use any type of container material, but if you think you may move the plant around for the best light, choose a lightweight material like plastic or composite.
• Select a site that is protected from wind and hot afternoon sun.
• Use a lightweight, well-draining potting soil for your hibiscus plants. Never use ordinary dirt for containers. You want a good quality soilless mix that’s amended with peat, coir, perlite or vermiculite.
• Container grown plants need fertilizer applications more often than in-ground plantings. This is due to water flushing the nutrients out of the pot. When planting, add a slow-release fertilizer to the potting soil. Throughout the growing season, apply a water-soluble fertilizer every two weeks.

In nature, perennial hibiscus grows along riverbanks and the edges of lakes. Similarly, in your garden, hardy hibiscus will need plenty of moisture. This makes it a reliable plant for a rain garden, or a swale in your landscape. Look for a space in your garden that gets good light and has a nearby water source.

Follow these tips for planting hibiscus in ground.

• For maximum visual impact, plant shrub and hardy hibiscus in mixed flower borders that feature shrubs, perennials and annuals.
• Pay attention to the mature height and width of the plants. Even hardy hibiscus can reach several feet across. Tall shrubs should be planted at least five feet away from structures like houses.
• Dig planting holes as deep as the root ball and twice as wide. Amend the soil with compost and a slow-release fertilizer.
• Before planting, thoroughly soak plants by placing in a bucket or galvanized tub filled with cool water. Remove from water and plant hibiscus so the crown is slightly above the soil level. Fill in with native soil amended with compost.
• Top planted hibiscus with mulch to help retain water and suppress weeds. Water after planting.
• Newly planted hibiscus plants need frequent irrigation to establish. In the hottest times of the year, you may need to water every day or every other day.

Keep your hibiscus blooming and healthy by providing water and fertilizer throughout the growing season. Newly planted hibiscus will frequently need water while establishing root systems. You’ll know it’s time to water when the leaves wilt or turn yellow. Dry soil is another indicator that it’s time to water. Use your fingertips to press into the soil. If it’s dry, then it’s time to water.

The same is true for hibiscus grown in containers. To cut down on hand watering, consider setting up drip irrigation to keep plants happy.

Fertilize hibiscus with an all-purpose liquid fertilizer during the growing season. Plants in containers will need more frequent fertilizer applications due to water flushing out nutrients in the soil.

Hibiscus plants don’t often need pruning, unless it’s to trim off dead branches and leaves. Hibiscus blooms on “new” wood, so trimming the plant will not prevent blooms for the coming season.

Hardy hibiscus will die back after first frost. Trim off the dead plant material and discard. When days warm in spring, the stems and blooms will come to life again, but slowly. Hibiscus are one of the last plants to emerge in spring.

In the right conditions, hibiscus plants are blooming machines. Follow these tips to get the most out of your hibiscus plants.

• Make sure your plant gets enough light. At least six hours of sunlight each day helps the plant bloom at its best.
• Hardy hibiscus plants get a slow start in spring. For best results, when you see the new spring growth, trim all stems to six inches. Feed with a slow-release fertilizer product.
• Make sure your plant has good drainage. Amend potting soil with organic compost and refresh landscape plantings with a top dressing of compost.

To keep your hibiscus plant looking fresh, remove spent blossoms.

Hardy and shrub hibiscus will thrive outdoors to zones 5 to 9. In the landscape, you can trim down the stems for winter, but it’s not necessary. Give the plant a blanket of mulch to help it through the winter.

Tropical hibiscus can be moved indoors if you live outside zones 10 to 12. Indoors, you can treat plants as houseplants and try to keep them blooming, or you can let them go dormant. The latter is usually the better option for overwintered hibiscus plants.

Tips for overwintering hibiscus plants:

• Before moving inside, trim off any dead or diseased foliage. If the plant is too big for your space, you can safely remove about a third of the plant’s growth.
• Spray plant with Neem oil to reduce the chance of bringing unwanted insects into your home.
• Thoroughly check over the plant for insects before bringing it inside.
• Indoors, you can move the plant to a sunny location. It will likely drop some of its leaves as it adjusts to lower light and drier air.
• If a sunny location isn’t available, place pot in a cool area in low light.
• Check frequently to make sure the plant’s roots don’t dry out. You want to soil to remain “barely moist.”
• When it’s time to move the plant outside in spring, begin the transition by “hardening off” the plant. Move the plant outside for a few hours each day and bringing it indoors each evening. Increase the time outside each day until it’s acclimated.