Rubber Plant Yellow Leaves and Leaf Drop: Causes and Solutions

The rubber plant (Ficus elastica) is an evergreen woody foliage plant with relatively large, thick leathery, glossy leaves that are round to oblong, dark green on the upper surface and pale green beneath. Placed in the home, it is a very lively plant, but sometimes small problems arise, such as rubber plant leaves turning yellow or even dropping. Today the editor introduces the causes and solutions for rubber plant leaves turning yellow and dropping:

Soil compaction caused by not repotting for a long time

[Cause] In the early growth stage, the rubber plant needs repotting once a year, with the pot diameter increasing year by year. After 6 to 8 years of growth, it can be repotted once every three years. If it is not repotted for a long time, the potting soil becomes severely compacted and soil aeration is poor, causing the fibrous roots of the rubber plant to suffocate and die, unable to absorb water and nutrients, which causes the leaves to turn yellow and drop.

[Solution] When the temperature reaches above 15°C, repot it, cut off the dead roots, and shake off most of the old soil. Remove the yellowed leaves, shorten the stem appropriately, and replace the compacted potting soil with fresh fertile culture soil. Keep the soil moist regularly to encourage new roots to grow, restore a healthy state, and grow into a multi-branched plant. In subsequent care, keep the potting soil well aerated. While keeping the potting soil moderately moist, loosen the potting soil once every 15 to 20 days to avoid root rot or root shrinkage caused by repeated watering leading to soil compaction.

No fertilization for a long time

[Cause] The rubber plant likes heavy fertilizer and abundant water. Not fertilizing for a long time causes nutritional deficiency, leading to yellowing leaves.

[Solution] Add an appropriate amount of base fertilizer when repotting, remove the yellow leaves, and thereafter apply liquid fertilizer once every half month, mainly phosphorus and potassium fertilizer.

Overwintering temperature too low

[Cause] The minimum suitable temperature for the rubber plant is above 6 to 8°C. If the indoor temperature in winter is below 5°C, leaves will turn yellow and drop.

[Solution] Raise the indoor temperature for overwintering, and be sure to keep it above 6 to 8°C.

Too much watering or fertilizing

[Cause] Although the rubber plant likes water and fertilizer, if watered or fertilized too much, especially from August to September when the weather is still rather stuffy and hot, excessive watering causes water to accumulate in the pot; or if watered too much during overwintering while the plant is dormant and transpiration is reduced, the water in the pot cannot drain in time; or if raw fertilizer, heavy fertilizer, or concentrated fertilizer is applied by mistake, root rot will occur due to water damage or fertilizer damage, causing leaves to turn yellow. If root rot is caused by fertilizer damage, the roots will be accompanied by an unpleasant odor.

[Solution] First cut off the rotted roots until the cut surface is fresh and white milky sap exudes. Let it air briefly until the sap at the wound dries, or apply sulfur powder to the wound for disinfection, or wipe the wound with clean plant ash or charcoal dust. At the same time, cut off part of the branches to reduce transpiration water loss, then repot it. When replanting, it is best to use clean, slightly moist fine sand to first surround the root wound, and on the outside use fresh, loose sandy loam to plant it. Strengthen shading and misting management, and do not water again until the potting soil is dry. As long as the root damage is not too severe, new fine fibrous roots will grow from the root wounds after one month. In subsequent care, just keep the potting soil slightly moist regularly; do not water excessively, and mist the leaves more in the morning and evening.

Lack of water

[Cause] Because the indoor air is too dry, the moisture in the potting soil is not enough to supply transpiration for all the leaves, causing some leaves, especially the lower old leaves, to turn yellow and even drop.

[Solution] Check the moisture level of the potting soil from time to time and replenish water in time. Mist the leaves in the morning and evening every day. If that is still not enough, mist the leaves again around noon. Note: the water temperature for watering and misting should be basically the same as the soil and room temperature. If the water temperature for watering and misting differs greatly from the soil temperature and air temperature, it can easily cause adverse physiological reactions.

Poor indoor ventilation

[Cause] If the room is not ventilated for a long time, harmful gases accumulate, such as excessively high carbon dioxide concentration, which can also cause yellow leaves.

[Solution] Open windows in time for ventilation, and keep the room ventilated and the air fresh to improve it. In winter, open doors and windows at noon when the temperature is relatively high to replace the indoor air.

Long-term shading

[Cause] The rubber plant is a tropical species that likes plenty of sunlight and cannot tolerate shade. If it does not get sunlight indoors for a long time, yellow leaves will also occur.

[Solution] Place the plant in a spot with sunlight.

Possible infection with gray mold

[Cause] Gray mold is a common fungal disease of open-field and protected crops that is relatively difficult to control. It is a low-temperature, high-humidity disease. The pathogen grows at 20 to 30°C. When the temperature is 20 to 25°C and humidity remains above 90%, it is a high-incidence period for the disease.

[Solution] Diseased leaves should be removed and burned promptly. Increase indoor light and raise the room temperature. Or alternately spray 50% vinclozolin wettable powder at 1200 times dilution, or 40% chlorothalonil wettable powder at 600 times dilution, once every 7 to 10 days, spraying continuously 2 to 3 times, which can effectively control the spread of the disease.