Is the Radermachera (China doll) suited to an acidic or alkaline soil environment?

The Radermachera likes a fertile, loose, airy and well-draining soil environment rich in organic matter. It is also moisture-loving but not drought-tolerant, and warmth-loving but not cold-tolerant, and the Radermachera shares many characteristics with the Cinnamomum kotoense (camphor tree). The Cinnamomum kotoense rather likes a slightly acidic soil environment, so what about the Radermachera?

Practice has proven that potted Radermachera grown in a slightly acidic soil environment tends to maintain good growth, while in slightly alkaline potting soil the plant's growth is less than satisfactory. It is clear that the Radermachera is a green plant that rather prefers an acidic soil environment. So when we mix potting soil for it, we should also consider the soil's pH, using acidic soil as the baseline.

In fact, the Cinnamomum kotoense can survive in acidic, neutral and mildly alkaline soil environments, and the pH of the potting soil should preferably be kept between 4.5-8.5. But when it comes to soil quality, it is recommended to use slightly acidic soil for growing the Radermachera. Moreover, the Radermachera has a relatively well-developed root system, so it is suitable to grow it in deep sandy loam. To make the potting soil slightly acidic, we can adjust the soil's acidity through various means.

1. Add edible vinegar

Adding an appropriate amount of edible vinegar to the potting soil can help increase soil acidity and make the potting soil more suitable for the growth of the Cinnamomum kotoense. But the amount of edible vinegar must be well controlled and cannot be too much; it can be diluted with water at a ratio of 1:30, and after mixing evenly, poured into the potting soil.

2. Use rice-washing water

Normally, after washing rice to cook, you can collect the water, put it into a larger container, seal it for 1-2 days, and then use it to water the potting soil. But when using rice-washing water, you also need to control the concentration well, and it likewise needs to be diluted with water before being applied to the potting soil. In this way, you can achieve the goal of acidifying the soil while not harming the plant.

3. Soak fruit peels in water

To obtain acidic water, we can collect leftover fruit, spoiled fruit, or even fruit peels, and put them into a sealable container. Then add an appropriate amount of water and seal the container mouth tightly to prevent air leakage, so that the contents ferment fully. After about 1-2 weeks, we can pour out the solution inside, dilute it, and use it to water the soil.

Of course, besides the above three methods, we can also add a small amount of ferrous sulfate, sulfur powder, etc. when watering the Radermachera, likewise taking care to control the amount. We can also directly use a low-concentration monopotassium phosphate solution (concentration controlled at 0.2%) to water the soil, which often achieves the goal of acidifying the soil. In short, there are many ways to keep the soil acidic, so you might as well try more and choose a method that suits you, as long as the acidity is kept within a reasonable range.