What are the cultivation methods and precautions for the Radermachera sinica (China doll)?

The Radermachera sinica is probably one of the most popular plants for home growing right now, alongside the Pachira aquatica (money tree), because both have a big advantage in their names and symbolic meanings, and home growers in particular tend to favour plants that stand for family happiness. But while buying a Radermachera sinica is very easy, is growing one just as easy? You will know once you see how the Radermachera sinica should be grown.

How to grow the Radermachera sinica

The Radermachera sinica is native to Taiwan, China, Guangdong, Hainan, Guangxi, Guizhou, Yunnan and other places, and is also distributed in India, the Philippines, Bhutan and other countries. It likes high temperatures, high humidity and plenty of sunlight, tolerates heat, fears cold, prefers moisture and dislikes dryness, and grows in sparse forests in valleys or on flat ground. For cultivation, use loose, fertile loam and sandy loam that drains well and is rich in organic matter.

Cultivation methods and precautions for the Radermachera sinica

1. Soil

The Radermachera sinica likes loose, fertile soil that drains well and is rich in humus. The soil mix for Radermachera sinica bought directly from outside is generally garden soil + leaf mould + decomposed organic fertiliser + river sand, mixed in a ratio of 5:3:1:1. These days, though, perlite or vermiculite is mostly added to the soil to prevent it from compacting.

2. Water

The Radermachera sinica likes a moist environment. During the growing period it not only needs relatively high ambient humidity but also a certain level of soil moisture. In spring, however, while the tender buds are sprouting and new shoots are emerging, water should be controlled appropriately to prevent the branches from growing leggy.

In spring, water once every 2 to 3 days; in summer and autumn, when temperatures are higher, water once every 1 to 2 days; in winter, control water appropriately and water once every 7 days. When watering, pay attention to the weather: choose a sunny day to water and do not water on cloudy days. In addition, during dry, hot seasons, spray the plant with water every day to maintain a certain humidity, so that the leaves do not lose water, turn yellow and drop.

3. Temperature

The Radermachera sinica likes a warm, hot and humid environment, and its optimum growing temperature is between 20 and 30 degrees. When the environment exceeds 30 degrees, shade it appropriately, increase humidity and spray the leaves, or move it to a cool, ventilated place. When the temperature drops below 10 degrees, move the Radermachera sinica into a shed. During the winter, keep the indoor temperature no lower than 8 degrees, and at minimum no lower than 5 degrees, to avoid cold damage or leaf drop.

4. Humidity

The Radermachera sinica likes a moist environment, and air humidity is generally kept at 70 to 80%. A well-ventilated bathroom has excellent humidity! For indoor placement at home, you can often spray the plant with slightly warm clean water to keep the leaves fresh and also increase air humidity.

5. Light

The Radermachera sinica likes light and tolerates slight shade; it can grow in either full sun or semi-shade.

The Radermachera sinica behaves differently at different growth stages. Seedlings are relatively shade-tolerant and only grow well with shading; mature plants are best placed by a window indoors with plenty of light, sometimes in full sun and sometimes in diffused light. If the Radermachera sinica grows in a dark environment for a long time, it easily drops its leaves.

6. Fertilising

Every year in April, as the temperature rises, move the Radermachera sinica outdoors to grow it, and when repotting, add a certain amount of compound fertiliser to the soil; once it enters the peak growing season, apply decomposed liquid fertiliser once a month, and after the Mid-Autumn Festival apply a phosphorus-potassium fertiliser once to strengthen the plant's cold resistance and ensure it overwinters safely.

Note that when the summer temperature is above 32°C or the winter temperature is below 12°C, fertilising should be stopped. At these temperatures the Radermachera sinica grows slowly and absorbs fertiliser poorly, so fertiliser that stays in the potting soil for a long time easily causes fertiliser burn.

7. Avoiding cold injury

Summer and winter are the hardest seasons for the Radermachera sinica: it is either hot or cold. Heat is manageable, but once it turns cold the plant is easily frostbitten. So after the start of winter, promptly move the Radermachera sinica indoors for care and keep the temperature above 10°C. If insulation measures are inadequate and the temperature stays below 5°C for a long time, cold damage is very likely, causing leaf drop.

8. Pests and diseases

The Radermachera sinica fears freezing in winter and stuffiness in summer, and a stuffy, hot environment easily leads to all kinds of pests and diseases. Take preventive measures in good time. Once small insects appear on the leaves, spray pesticide immediately and improve ventilation. If leaves turn yellow and drop, promptly clean away the yellowed leaves and spray a fungicide.

Layering propagation of the Radermachera sinica

Layering is the least labour-intensive method, but its drawback is that if the layering is done improperly, you will neither produce a new plant nor get the layered branch to grow well.

1. Timing of layering

Spring each year is the growing season for the Radermachera sinica, and layering at this time can increase the survival rate. In addition, if layering is unsuccessful, cut the branch back promptly so it can grow again.

2. Layering method

Choose a two-year-old branch and girdle it at the lower end; the width of the girdle should be 2 to 3 times the diameter.

Then wrap the girdled area in mud and press it into a ball of soil 8 to 10 cm in diameter. Then wrap the soil ball in plastic film, leaving a small opening at the top for watering. Then tie the girdled branch against a thick, sturdy branch to secure it, so that the branch does not break and affect growth.

After three seasons, by autumn, a fairly complete root system will have grown at the girdled area; at this point it can be cut off and potted separately.

Flowering period of the Radermachera sinica

The flowering period differs somewhat with the environment. The Radermachera sinica generally flowers from May to September each year, varying with environmental differences, and it does not often flower in northern regions. Generally, a Radermachera sinica grown from seed takes relatively longer to reach flowering, while one propagated by cuttings or layering will flower in 2 to 3 years. When the Radermachera sinica blooms, the flowers are relatively small and delicately coloured, yellow to pale yellow, and unscented. Yet they give people a feeling of closeness.

The Radermachera sinica is a plant that very easily creates a sense of warmth and closeness; not only is its name very approachable, but even the flowers it produces are very approachable yellow blooms, so growing a Radermachera sinica at home is undoubtedly very fitting, and the Radermachera sinica is not especially difficult to grow.