What's going on with the yellow leaves of gardenias?
If you want to understand why gardenias have yellow leaves and the related knowledge of gardening methods and precautions for small-leaf gardenias, let's learn about them together.
The blooming of gardenias is very beautiful. For those who know how to care for them, it's easy to keep their leaves green and make them bloom abundantly, with a delightful fragrance. However, for many新手 gardeners, gardenias are not easy to grow. The most common problem is the yellowing of their leaves. So, what causes the yellowing of gardenia leaves, and how should we solve this problem? How can we grow gardenias well?
There are two types of yellow leaves in gardenias. One has green veins with the rest of the leaf turning yellow, which is the most common and widespread case. The second case is when the lower leaves start yellowing from the veins, gradually spreading to the entire leaf and eventually falling off. Let's first discuss the first case, where the veins are green and other parts are yellow. The main reason for this is the alkalinity of the potting soil. Generally, in the north, the potting soil and water quality are alkaline, while gardenias, being a flower from the south, prefer acidic soil and require a large amount of iron. If the potting soil is alkaline, it will inevitably lead to yellow leaves. Initially, this situation occurs in newly grown leaves and later spreads to the whole plant. If detected early, promptly water with iron sulfate, diluting it to a concentration of 1:1000, and add a couple of drops of vinegar to the potting soil, which will definitely improve the condition. If severe yellowing occurs and the whole plant is affected, change the pot and the soil to allow it to grow new roots, and supplement with iron sulfate to effectively alleviate the condition, preventing it from happening again later.
The second case, where the veins turn yellow, is due to the plant's roots being damaged after recently being repotted, resulting in insufficient nutrient absorption and supply, or a lack of fertilization during the maintenance process. If you find that the lower leaves of your gardenia are yellowing and falling off, check if it has been repotted. If it has just been repotted, ensure the potting soil remains moist and is watered sufficiently, which will help it grow roots quickly. Once the root system is established, this condition can be alleviated. If you've been growing it for many years, it's likely lacking in fertilizer or the potting soil is compacted and nutrient deficient. Either repot it or supplement with fertilizer.
Gardenias are actually not difficult to grow. During maintenance, ensure they get plenty of light, use a smaller, shorter pot, and maintain the soil's breathability and water permeability. You can add some well-fermented pine needles to the soil to ensure its acidity. Water with iron sulfate once a month and water thoroughly when the soil surface is dry. As long as the temperature does not drop below 10 degrees, it can grow normally. When it's time to bloom, supplement with phosphorus and potassium fertilizer, and it will bloom quickly. It's a very easy plant to grow; you just need to master the right care methods.
The above introduction to why gardenias have yellow leaves and the comprehensive method of growing small-leaf gardenias and precautions, I hope it can act as a starting point to solve your problems with green plants.