Hibiscus care

The Hibiscus varieties (Chinese, Tropical, Rose of Sharon) require similar care. Pruning is due in spring and autumn, and it can be propagated from seeds or cuttings.

One of the most popular Mediterranean plants is Hibiscus, which can reach a height of 6 - 10 feet (2 - 3 meters). The most well-known Hibiscus varieties are the Chinese Hibiscus (or Tropical Hibiscus), the Swamp Rose Mallow Hibiscus, and the Rose of Sharon (simply called mallow). Hibiscus is not only attractive in gardens but also on terraces, in winter gardens, or hallways. Due to its large, simple or double flowers and vibrant color range, it has become a very popular garden and indoor ornamental plant.

If we provide the right conditions, it can bloom all year round in our homes. Unfortunately, its huge funnel-shaped flowers only last for one or two days, but it compensates with an abundant bloom throughout the year. This beautiful Mediterranean plant dazzles in many colors, ranging from white to pink, yellow, and burgundy.

The Hibiscus or Rose of Sharon is one of the most diverse genera of the mallow family (Malvaceae), belonging to the dicotyledons (Magnoliopsida), with around 1,200 species. Due to its striking flowers, many species are cultivated worldwide as ornamental plants. It originates from Asia. Some varieties are typical invasive plants, while others have been spread worldwide by humans. Most Hibiscus species thrive in tropical, subtropical, and warm temperate climates. Among them, we can find annuals and perennials, woody and herbaceous plants, deciduous and evergreen types.

Common Hibiscus varieties and their popular names:

• Chinese Hibiscus, Tropical Hibiscus (Hibiscus rosa-sinensis)
• Swamp Rose Mallow Hibiscus, Hardy Hibiscus (Hibiscus moscheutos)
• Rose of Sharon (Hibiscus syriacus)
• Kenaf (Hibiscus cannabinus)
• Scarlet Rose Mallow (Hibiscus coccineus)
• Variegated Hibiscus (Hibiscus purpurea)
• Roselle, Florida Cranberry, Sudanese Hibiscus (Hibiscus sabdariffa L.)
• Fringed Hibiscus, Coral Hibiscus (Hibiscus schizopetalus or Hibiscus rosa-sinensis var. schizopetalus)
• Confederate Rose Mallow, Cotton Rose (Hibiscus mutabilis)
• Flower-of-an-hour (Hibiscus trionum)

We can keep Hibiscus not only in the garden but also in a bright and cool hallway or winter garden. Plant it in a large, beautiful pot, or if we want to create a true Mediterranean atmosphere, choose a large ceramic flower pot. In Mediterranean countries, Hibiscus is often planted as a hedge. We often see such solutions in gardens and public squares. It is worth trying this in our garden too.

Hibiscus care

The most important requirements for Hibiscus care are regular nutrient supplementation from spring to autumn and spring and autumn pruning. The more we prune the plant, the more flowers and denser growth we get. A healthy Hibiscus plant does not have a dormant period and can bloom all year round if the temperature conditions are right.

With consistent fertilization, the plant will continuously produce beautiful flowers. If we choose to grow this tropical beauty in a container, we avoid problems with nematodes and other pests, as well as drought, frost, and nutrient deficiency.

Light requirements for Hibiscus

Hibiscus loves bright, well-lit spaces and adores the summer sun. From spring to autumn, keep it in a sunny or very bright spot, as it needs 6-8 hours of direct sunlight daily. The best is to provide direct sunlight in the morning and late afternoon, while during the hottest hours, some shade is beneficial.

Indoors, place it in a sunny window where it can get several hours of direct sunlight, or we can grow it on the veranda or in a winter garden. When bringing an indoor Hibiscus outdoors for the first time in the season, gradually acclimate it to strong sunlight, otherwise, its leaves may burn. This is equally true for any Hibiscus that has been kept indoors and is being moved outside for the first time that year.

Although Hibiscus loves direct sunlight, it can tolerate some shade, especially during the hottest hours of the day. Insufficient light slows its growth and reduces flowering, while too much direct sunlight may cause it to drop its flowers and leaves.

Temperature requirements for Hibiscus

Due to its tropical origin, Hibiscus flower is a heat-loving plant. In summer, it thrives best at 64 - 90 °F (18 - 32 °C). Although it tolerates heat well, prolonged exposure to extreme temperatures without adequate watering can stress the plant.

Some varieties are more sensitive to the cold, such as the Chinese Hibiscus, also known as Tropical Hibiscus, which requires a minimum temperature of 50 °F (10 °C). Below this temperature, it may not survive. Other Hibiscus varieties can stay outdoors as perennials even during winter, enduring minor frosts easily. This includes the Rose of Sharon and the Swamp Rose Mallow Hibiscus, which, if well-established during the summer, can be safely overwintered in the garden.

In spring, after the frost has passed, we can move indoor Hibiscus varieties outdoors. In winter, keep it in a cooler, bright place at 50 - 54 °F (10 - 12 °C). Avoid overwintering it in a warm, heated room, as it will hardly or not at all bloom under such conditions.

Watering needs for Hibiscus

Many Hibiscus growers water and fertilize their plants once a week. This can be sufficient, but with daily watering, the plant is maximally guaranteed access to nutrients. The soil should always be moist, but not waterlogged.

If kept in a pot, pour out the excess water from the saucer. If the air is too dry, mist the plant with chlorine-free water. In winter, reduce watering frequency.

Generally, during hot weather, Hibiscus requires more frequent watering. Monitor it — if the top 1 - 1.5 inches (2 - 3 cm) of soil feels dry to the touch, it is time to water.

Planting and Repotting Hibiscus

The ideal soil for planting Hibiscus is light and porous. It should allow air and water to pass through easily while retaining some moisture. A recommended mix consists of two parts soil, two parts peat, and one part fine bark. If using garden soil for container growing, improve its physical structure and water and nutrient retention capacity by adding peat, bark, compost, perlite, and sand.

Smaller Hibiscus plants can be repotted annually into a slightly larger pot. Choose loose, well-draining potting soil. A mix of compost and general-purpose potting soil works well, or you can use B-type potting soil available in garden stores.

Larger plants should only be repotted every two to three years; after that, just replace the top layer of soil. Always choose a pot that is just one size larger for repotting, so the plant doesn’t focus solely on root growth and still has energy for new shoots.

Fertilizing and Nutrient Supplementing Hibiscus

Use only commercially available plant fertilizers, and always read the label carefully. Dissolve liquid or powdered fertilizer in water and apply it to the soil surface.

Granular fertilizers and tablets provide gradual and even nutrient release during the selected treatment period. It is beneficial to use complex plant fertilizers that also contain micronutrients.

Overwintering Hibiscus

Perennial Hibiscus varieties such as Rose of Sharon (Hibiscus syriacus) and Swamp Rose Mallow Hibiscus (Hibiscus moscheutos) can remain in the garden even in frost-prone areas, provided they have grown strong over the summer. However, you can provide extra protection by covering the base of the plant with mulch, leaves, or other insulating ground covers. If grown in a container or pot, it's advisable to move it to a frost-free location, as its roots are more exposed than if it were planted directly in the ground.

Non-hardy Hibiscus varieties, such as Chinese Hibiscus or Tropical Hibiscus (Hibiscus rosa-sinensis), should be overwintered indoors in a place where the temperature is at least 50 °F (10 °C), but ideally between 59 - 70 °F (15 - 21 °C).

During the overwintering period, Hibiscus still needs plenty of sunlight, so place it in a location where it can receive ample light.

Reduce watering during overwintering, as the plant enters a dormant state due to the cold and grows less or not at all. Let the soil almost dry out between waterings.

In winter, if indoor heating makes the air too dry, it is recommended to increase humidity for the plant. This can be done by placing pebbles in a tray and filling it with water, then placing the pot on top of the pebbles. Ensure the pot sits on the stones, not directly in the water.

Pruning Hibiscus

Pruning Hibiscus is highly recommended to promote denser, bushier growth and increased flowering since hibiscus only produces flowers on new shoots. Pruning also helps to remove damaged branches.

Prune once in spring and once in autumn, and you can also shape the plant through pruning. For overwintered plants, prune them back heavily at the start of spring to encourage abundant flowering the following year.

For younger plants, cut back to encourage more branching.

When pruning Hibiscus, always leave the first leaf on the outer side of the branch to encourage outward growth.

You can also shape Hibiscus through pruning. It can be trained into a hedge, multiple small bush forms, or even a tree shape. However, shaping it into a tree form requires more than just pruning.

Training Hibiscus into a Tree Form

The Rose of Sharon (Hibiscus syriacus) and the Chinese Hibiscus or Tropical Hibiscus (Hibiscus rosa-sinensis) are the best candidates for shaping into a tree form. The simplest method is to leave a few strong stems and cut off the side shoots growing from them. This is an ongoing task; as the plant grows, keep removing the lateral shoots until the desired height is reached. If necessary, provide support to ensure the trunk grows straight. Upward, shape the canopy as desired.

Another option is to create a Braided Trunk Hibiscus tree form. This is a bit more challenging but can be done with patience and attention. Choose 3 - 4 strong main shoots, or plant 3 - 4 strong shoots close together. Continuously remove the side shoots from these stems and, while they are still green and flexible, start braiding them. Keep the braid somewhat loose to allow space for the stems to thicken. This process takes time, as the braiding must continue until the desired trunk height is reached. Shape the canopy through pruning to achieve the final tree form.

A unique feature of the Braided Trunk Hibiscus tree is that you can choose flowers of different colors, so the canopy will bloom in multiple colors. You can either let the branches intertwine naturally or guide them to ensure that each side of the canopy has flowers of different colors.

Propagating Hibiscus

Propagating Hibiscus from Seeds

Propagating garden Hibiscus varieties from seeds is relatively simple, as insects readily pollinate them outdoors. Once the seeds are collected, store them in a dry place, then sow them in early spring, around the beginning of March.

Growing seedlings is not particularly difficult, but it does require attention. It is advisable to sow 2-4 seeds in small pots and then remove the weaker seedlings after they sprout. By the second year, they can be planted outdoors.

Indoor Hibiscus varieties are more demanding. Since they are often cultivated through selective breeding, their reproductive capacity is significantly reduced. They are less likely to be pollinated successfully, and the seeds are less likely to mature. If you do manage to obtain seeds, the process is the same as for garden varieties, with the key difference being that these seedlings are more sensitive to cold and drafts.

Propagating Hibiscus by Cuttings

In most cases, Hibiscus is propagated through stem cuttings. This can be challenging, as the cuttings do not always root successfully. You can try rooting them in sand, peat, or water, but horticultural books often recommend using rooting hormones as well.

Rooting powders are commonly available in garden stores. While not mandatory, they are recommended if you want to ensure successful rooting.

The key is to select a young, non-woody, and completely healthy stem. Remove the lower leaves and plant the cutting in moist peat or sand. A loose soil structure is important, as it facilitates root development.

Cover the planted cuttings with plastic wrap and place them in a semi-shaded location. Check the moisture level regularly, as once the peat dries out, it can be difficult to rehydrate. If the cutting successfully roots, keep an eye out for pests as well.

Hibiscus Diseases, Pests, and Causes of Decline

Hibiscus Diseases

• Powdery mildew appears as a white, powdery coating on leaves, stems, and even buds. It is a fungal infection often caused by high humidity or poor air circulation.
• Rust is another fungal disease, characterized by rusty discoloration on the underside of leaves. It can cause leaf yellowing, leaf drop, and stunted growth. It develops in humid, wet conditions and poor air circulation.
• Leaf spot can be caused by fungal or bacterial infections, resulting in circular or irregularly shaped spots on the leaves. These spots can be brown, black, or yellow. Remove infected leaves and treat the plant with a fungicide.

Hibiscus Pests

• Aphids and other pests are common attackers of Hibiscus, so it is advisable to apply preventive treatments in spring and autumn to eliminate pests before they emerge. Inserting a clove of garlic into the soil may also deter pests. In spring, you can spray the plant with nettle infusion, followed by chemical treatment if necessary.

Environmental Factors and Improper Care of Hibiscus

• Overwatering - When the plant is left standing in water, the roots can become susceptible to fungal infections, leading to root rot.
• Yellowing leaves can occur due to inadequate or excessive watering or sudden temperature changes.
• If the leaves wilt or drop, cutting back the plant slightly may encourage new leaf growth. Excessive direct sunlight or overwatering can also cause wilting and leaf drop.
• Bud drop is a common issue where the buds fall off before opening. This is not a disease but a physiological disorder often caused by environmental stress such as temperature fluctuations, improper watering, or insufficient light.