How to grow potted hibiscus? A detailed guide to the latest care methods

The scientific name of hibiscus is Hibiscus rosa-sinensis, also known as red hibiscus, large red flower, zhuangyuan red, etc. It is an evergreen shrub of the genus Hibiscus in the mallow family, native to China. In ancient times it was already a popular ornamental plant, with large and brilliantly colored flowers that bloom in all four seasons, mainly used for garden viewing, and is widely cultivated around the world, especially in tropical and subtropical regions. Now let us take a look at how to grow potted hibiscus!

Growth habits of hibiscus

Hibiscus is a strongly sun-loving plant. It prefers warmth and humidity, requires ample sunlight, and is not tolerant of shade, cold, or drought. In the Yangtze River basin of China and areas to the north, it can only be grown in pots, and must overwinter in a greenhouse or other protected area with the temperature kept at 12-15°C. When the room temperature is below 5°C, the leaves turn yellow and drop; below 0°C, it suffers cold damage. It tolerates pruning well and has strong branching ability. It adapts to a fairly wide range of soils, but grows best in slightly acidic loam rich in organic matter with a pH of 6.5-pH 7.

Propagation methods of hibiscus

1. Cuttings: Usually done from May to October, or in winter in a greenhouse, but the survival rate is highest during the plum rain season. The best cuttings are one-year-old semi-lignified ones, 10 cm long, with the lower leaves removed and the top leaves retained. The cut should be flat, and the cuttings are inserted into a sand bed while maintaining relatively high air humidity, with a room temperature of 18-21°C; roots form 20-25 days after insertion. Treating the base of the cuttings with 0.3-0.4% indolebutyric acid for 1-2 seconds can shorten the rooting period. When the roots are 3-4 cm long, transplant them into pots.

2. Grafting: Usually done in spring and autumn, mostly used for hibiscus varieties that are difficult to root from cuttings or root slowly, especially double-petaled varieties with a low cutting survival rate. Either branch grafting or bud grafting can be used. The rootstock is single-petaled hibiscus, and grafted seedlings grow branches and bloom in the same year.

Cultivation methods for hibiscus

1. Light: Hibiscus is a sun-loving species. In early May it should be moved outdoors to a sunny spot. If light is insufficient, flower buds tend to drop and flowers become smaller. Daily sunlight must not be less than 8 hours.

2. Fertilizing: During the growing season, hibiscus has a relatively high demand for fertilizer. Apply a dilute liquid fertilizer once every 7-10 days.

3. Watering: During the growing period, hibiscus needs sufficient water; it must neither lack water nor become waterlogged. Usually water once a day, and during the dog days of summer, once in the morning and once in the evening. Sprinkle water on the ground frequently to increase humidity and lower temperature, preventing tender leaves from scorching and flowers from dropping early.

4. Overwintering: After the weather turns cool at the end of October, move hibiscus into a greenhouse and keep the temperature above 12°C. Management after autumn should be careful, and less fertilizer should be applied later to avoid producing autumn shoots. Autumn shoots are tender and have weak cold resistance, and will suffer cold damage in cold weather.

5. Pruning: Hibiscus can be pruned and shaped in early spring before and after being moved outdoors. Except for leaving 2-3 buds at the base of each branch, cut off all the upper parts. Pruning can promote new branches, making growth more vigorous and the plant shape more attractive. After pruning, because the aboveground part consumes less, water and fertilizer should be appropriately controlled.

6. Repotting: For potted hibiscus, the soil should be loose, fertile sandy loam. Before moving it outdoors in early spring each April, it should be repotted. When repotting, replace with new culture soil, cut off some overly dense and curled fibrous roots, apply sufficient base fertilizer, and add a little phosphate fertilizer at the bottom of the pot.

Pest and disease control of hibiscus

1. Leaf spot disease

[Harm] It mostly occurs in late autumn when the weather turns cold, and is even more likely to occur in northern regions when plants are not moved into storage in time. The initial symptom is pale yellow and red-yellow spots on the leaves. After the spots expand, they become round or oval. Under relatively humid conditions, black granular bodies may appear on the spots, namely the pathogen's pycnidia. In the later stage, the leaves dry up and drop.

[Control] The key to control is doing a good job of cold protection. When strong winds and cooling occur after autumn, take protective measures. On this basis, promptly spraying 500-800 times diluted zineb or 1500 times % ammonium can both achieve very good control results.

2. Stem rot

[Harm] It mostly occurs during the rainy season, and is severe under high temperature and rainy conditions. The pathogen mostly infects from the junction of the roots and stems of the plant. The early symptoms are not very obvious; only the cortex at the affected site shrinks and appears slightly dark brown, but the tissue beneath the skin has already begun to rot and turns brown. After the lesion encircles the stem, the plant dries up and dies. From the leaf surface, in the early stage of disease, the leaves wilt, yellow-brown necrotic spots appear at the edges, and gradually expand inward; in the later stage, the leaves dry up and drop.

[Control] The key to control is preventing long-term washing of the plant by heavy rain, and around the rainy season applying 200-500 times diluted thiophanate to the trunk every 10 days or so. Experiments show that this method has very good control results.

3. Root-knot nematode disease

[Harm] Root-knot nematode disease is also a widely distributed and seriously damaging disease. Observed from the aboveground part, in the early stage the leaves grow weakly and red-brown necrotic spots appear at the edges. They expand inward, and in the later stage the leaves dry up and drop. Observed from the underground part, tumor-like growths of various sizes are found among the plant roots. They are smooth and flesh-colored in the early stage, and rough and brown in the later stage, containing pear-shaped female nematodes the size of needle tips.

[Control] Control is relatively difficult. If there are few plants, the soil can be replaced; the soil must be exposed to the sun for a relatively long time, and the old soil should not be used again. For more plants, aldicarb granules can also be applied, planned at about 0.5 g buried per 5-inch pot.