Poinsettia leaves yellowing and the leaves may be caused by low temperature, uneven sunshine, improper watering and unreasonable fertilization. Reasonable adjustments should be made according to plant-related reasons. During the growth of poinsettia, proper temperature, sufficient light, suitable moisture and fertilizer conditions are needed to make the plant grow better.
If the temperature is too low, the leaves of poinsettia will turn yellow and fall off. Poinsettia is suitable for growth between 15 and 20 degrees. It is very hot in summer. If the temperature of plant growth is above 30 degrees, the high temperature will damage the leaf tissue and make it dry and yellow. If the plant is exposed to high temperature for a long time, the leaves will turn yellow and fall off, which will eventually cause the plant to die.
Uneven sunlight will cause the poinsettia leaves to yellow and fall off. If the light time is too short, it will affect the leaf color and make it unable to perform photosynthesis normally. Excessive light will sun damage the leaves, affect the growth of the leaves, cause the leaves to breathe abnormally, and cause the leaves to gradually turn yellow and eventually fall.
Improper watering will cause the leaves of poinsettia to turn yellow and fall off. Poinsettia is suitable for watering once every 2 days. If the water is too much, the roots of the plant will rot, which will affect the plant's transmission of water and nutrients to the leaves, and the water and nutrition of the leaves will become dry and yellow. If there is too little water, the leaves of the plants will dry out and turn yellow under the condition of lack of water, which will eventually cause the leaves to yellow and fall off.
Irrational fertilization will cause poinsettia leaves to yellow and fall off. Poinsettia needs to be fertilized about once every 15 days during growth. Lack of fertilizer will make the plant malnutrition and cause the leaves to shrink and yellow. Excessive fertilization will burn the roots of the plant, making it impossible for the roots to properly absorb nutrients, resulting in dry leaves, yellowing and eventually shedding.