Reasons for Yellowing Leaves on Osmanthus Trees and How to Fix Them, and Why You Cannot Grow Them at Home

Osmanthus is one of China's ten traditional famous flowers. Osmanthus, also known as muxi, yangui, or yuegui, is an evergreen shrub or small tree in the family Oleaceae. There are golden osmanthus, silver osmanthus, dan osmanthus, and yuegui, among others. So what causes osmanthus leaves to turn yellow? How do you fix it? Why can't you grow osmanthus at home? Let me answer these questions for you.

I. What causes yellowing leaves on osmanthus trees? How do you fix it?

Many flower growers always run into yellowing leaves when growing osmanthus. Some figure out the cause themselves, but more growers have no idea what is causing it. Below I have put together the reasons for yellowing osmanthus leaves and the solutions, so you can troubleshoot on your own.

1. Overwatering causes osmanthus leaves to turn yellow (water yellowing): Too much watering leaves the potting soil waterlogged and wet for long periods, causing a lack of oxygen in the soil, which leads to rot in some fibrous roots. This weakens the ability to absorb water and nutrients, causing young leaves to turn pale yellow, and the leaves gradually turn dark yellow one after another.

Solution: Once you notice it, immediately cut back on watering, stop fertilizing, and loosen the soil regularly so the potting soil gets good aeration. In severe cases, you need to take the whole root ball out of the pot and place it in a mound of dry soil so the moisture drains out quickly. Once the drooping branches and leaves recover, replant it in the pot.

2. Long-term lack of water causes osmanthus leaves to turn yellow (drought yellowing): Watering too little, or watering only the surface or missing waterings over a long period, makes leaves lose water faster than they take it in. This causes water supply to fall short of demand and also leads to yellowing leaves. "Drought yellowing" starts from the lower leaves, which gradually turn yellow, scorch, and drop upward, and in severe cases the leaf stalks droop and appear wilted.

Solution: Immediately move the pot to a cool place, mist the leaves with some water, and water lightly. Then, as the stems and leaves gradually perk up again, slowly increase the amount of water. If you suddenly water too much at this point, it can cause plasmolysis, damage the protoplasm, and kill the plant.

3. Excessive sun exposure causes osmanthus leaves to turn yellow (scorch yellowing): In summer, placing flowers that prefer partial shade and fear high heat in a spot with direct strong light easily causes young leaf buds or leaf edges to scorch, or the whole leaf to turn yellow.

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

4. Too-acidic soil causes osmanthus leaves to turn yellow (light-deficiency yellowing): In southern China the soil is red earth, which is acidic or slightly acidic. Magnesium in the soil is easily leached away, and when leaves lack magnesium, the older leaves and the areas between the veins first turn green then yellow. Calcium-magnesium phosphate fertilizer can be applied; plants like lucky bamboo will also suffer and develop yellowing, dropping leaves.

Solution: Therefore, after bringing it indoors, apply or spray a 0.1% to 0.3% magnesium sulfate solution as needed. To improve acidic soil, increase applications of rotted organic fertilizer and apply lime. Applying a small amount of lime not only neutralizes soil acidity but also promotes the decomposition of organic fertilizer.

5. Overfertilizing osmanthus causes leaves to turn yellow (fertilizer yellowing): Overfertilizing, especially too much nitrogen fertilizer combined with a lack of phosphorus and potassium fertilizer, easily causes leaves to turn yellow. It shows up as new leaves being thick and fleshy with mostly uneven surfaces, while old leaves gradually turn yellow and drop. In severe cases the leaf tips dry up, and even whole leaves turn scorched yellow.

Solution: If this happens, stop fertilizing immediately 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 (nutrient-deficiency yellowing): Insufficient fertilization, especially not applying nitrogen fertilizer or not changing the potting soil for a long time, leaves the soil lacking nitrogen. This causes branches and leaves to become weak, with thin, yellow leaves.

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

7. Pests and diseases cause osmanthus leaves to turn yellow: For soilless potted osmanthus, the main pests are grasshoppers and red spider mites, as well as white grubs. Grasshoppers feed on tender shoots and new leaves in summer and fall, easily leaving many leaves tattered and affecting the potted plant's appearance and growth.

Solution: You can use 4.5% beta-cypermethrin emulsifiable concentrate at 2000 to 3000 times dilution, or 40% chlorpyrifos emulsifiable concentrate at 1000 times dilution, and spray.

II. Why can't you grow osmanthus at home?

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

The Classic of Yin and Yang Dwellings says: "Osmanthus in the courtyard, ghosts return outside the house." In ancient and modern times, the osmanthus tree has been seen as an omen of misfortune in the home. It also says: "With an osmanthus tree before the gate, noble people stand within the door." 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 is believed to draw malevolent spirits into the courtyard, which is inauspicious and unfavorable and often invites quarrels.

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

Osmanthus can be grown at home; whether you can grow it 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 lush and it blooms profusely, while in shade its branches and leaves grow sparse and it flowers little. If grown in pots indoors in the north, special attention must be paid to giving it sufficient light to support growth and flower bud formation.

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