Why osmanthus tree leaves turn yellow, causes and solutions, and why you should not grow it at home

Osmanthus is one of China's ten traditional flowers. Osmanthus, also known as muxi, yangui, and yuegui, is an evergreen shrub or small tree of the Oleaceae family. It includes golden osmanthus, silver osmanthus, reddish osmanthus, and yuegui, among others. So what causes osmanthus tree leaves to turn yellow? How do you solve it? Why should you not grow osmanthus at home? Let me answer that for you.

1. What causes osmanthus tree leaves to turn yellow? How do you solve it?

Many flower growers always run into yellowing leaves when growing osmanthus. Some find the cause themselves, but more growers have no idea what is actually causing it. Below I have put together the causes of yellowing osmanthus leaves and the solutions, so you can check them one by one.

1. Overwatering causes osmanthus leaves to turn yellow (water yellowing): too much watering leaves the potting soil waterlogged and wet for a long time, causing a lack of oxygen in the soil, which makes some fibrous roots rot. As a result, the ability to take up water and nutrients weakens, causing young leaves to turn pale yellow, and the leaves gradually turn dark yellow as well.

Solution: once you notice it, immediately cut back on watering, stop fertilizing, and loosen the soil regularly so the potting soil is well aerated. In severe cases, you need to take the whole root ball out of the pot, place it in a pile of dry soil so the moisture seeps out quickly, and replant it in the pot once the drooping branches and leaves have recovered.

2. Long-term lack of water causes osmanthus leaves to turn yellow (drought yellowing): too little watering, or watering only halfway or missing waterings for a long time, makes the leaves lose more water than they take up, so the water supply cannot meet demand, which also causes leaves to turn yellow. “Drought yellowing” starts with the lower leaves gradually turning yellow, scorching, and dropping, and in severe cases the petioles droop and look wilted.

Solution: immediately move the pot to a shady spot, mist some water on the leaves, and give a small amount of water. Then, as the stems and leaves gradually perk up again, gradually increase the amount of water. If you suddenly give too much water at this point, it can cause plasmolysis and damage the protoplasm, which can kill the plant.

3. Scorching sun causes osmanthus leaves to turn yellow (sunburn yellowing): in summer, putting flowers that like partial shade and fear high heat in a spot with strong direct sunlight makes the young leaf buds or leaf margins scorch, or the whole leaf turn yellow.

Solution: immediately move it to a well-ventilated, cool place to grow.

4. Acidic soil causes osmanthus leaves to turn yellow (light-deficiency yellowing): southern China has red soil, and the soil is acidic or slightly acidic, so magnesium is easily leached from the soil. Due to magnesium deficiency, the leaves often show yellowing first between the veins of the old leaves. Applying calcium-magnesium phosphate fertilizer to plants such as lucky bamboo can harm them, causing leaves to turn yellow and drop.

Solution: therefore, after bringing the plant indoors, apply or spray a 0.1% to 0.3% magnesium sulfate solution as needed. To improve acidic soil, pay attention to applying more decomposed organic fertilizer and applying lime. Applying a small amount of lime can not only neutralize soil acidity but also promote the breakdown of organic fertilizer.

5. Overfertilizing osmanthus causes leaves to turn yellow (fertilizer yellowing): too much fertilizer, especially too much nitrogen fertilizer with a lack of phosphorus and potassium fertilizer, tends to cause leaves to turn yellow, showing as new leaves that are thick and mostly uneven on the surface, while old leaves gradually turn yellow and drop. In severe cases the leaf tips dry up, and even the whole leaf becomes scorched yellow.

Solution: when this happens, immediately stop fertilizing and increase watering so the fertilizer flows out through the drainage holes, or immediately repot, remove some of the old soil, rinse the root ball with water, replace part of it with fresh potting soil, and replant the plant in the pot.

6. Long-term lack of fertilizer causes osmanthus leaves to turn yellow (fertilizer-deficiency yellowing): insufficient fertilization, especially no nitrogen fertilizer or no repotting for a long time, means the soil lacks nitrogen, causing weak branches and leaves and thin, yellow leaves.

Solution: promptly repot, take the plant out, move it into a pot one size larger, fill it with fresh loose, fertile potting soil, and replant it. Water thoroughly, then place it in partial shade to recover. Once it resumes growth, apply a dilute liquid fertilizer or compound fertilizer.

7. Pests and diseases cause osmanthus leaves to turn yellow: in soilless potted osmanthus, the main pests are locusts and red spider mites, as well as white grubs. Locusts feed on young shoots and new leaves in summer and autumn, easily leaving many leaves damaged, which affects the appearance and vigor of the potted plant.

Solution: you can use a 4.5% beta-cypermethrin emulsifiable concentrate at 2000 to 3000 times dilution or a 40% chlorpyrifos emulsifiable concentrate at 1000 times dilution as a spray.

2. Why should you not grow osmanthus at home?

The idea that osmanthus cannot be planted comes basically from old sayings.

The Classic of Yin-Yang Dwellings says: osmanthus in the courtyard, ghosts return outside the house. In ancient and modern times, the osmanthus tree has been seen as a sign of misfortune and disaster in the home. It also says: with an osmanthus tree in front of the gate, a noble person stands inside the gate. So osmanthus is not beneficial to plant inside the gate; if planted in front of or behind the gate it is an auspicious sign, but if planted inside the courtyard gate it draws in ominous minor ghosts, which is unlucky and inauspicious and often invites quarrels.

Although this is a superstitious belief, it just depends on whether you believe it or not.

Osmanthus can be grown at home; whether it cannot be grown just depends on whether you follow superstition.

Osmanthus likes warmth and has strong stress resistance; it tolerates both high temperatures and fairly cold conditions. Osmanthus prefers sunlight but also tolerates shade. In full sun its branches and leaves grow luxuriantly and it blooms profusely, while in shade it grows sparse branches and leaves and bears few flowers. If grown indoors in pots in the north, you especially need to make sure there is enough light to support growth and flower bud formation.

Osmanthus grown at home is best placed on a balcony or in a courtyard spot that gets more sunlight, which benefits its normal growth and flowering.