The Chinese Evergreen (Aglaonema) is a popular houseplant valued for its striking, colorful foliage and tolerance for lower light conditions. When its vibrant leaves begin to turn yellow, it is a clear sign that the plant is experiencing stress. Yellowing is not a single diagnosis but a general symptom, indicating that the plant cannot produce sufficient chlorophyll, the green pigment necessary for photosynthesis. Troubleshooting the specific cause requires a careful examination of the plant’s environment and care routine.
Watering and Drainage Problems
Improper soil moisture is the most frequent cause of yellow foliage in Chinese Evergreens. Overwatering creates a waterlogged environment, which suffocates the roots by displacing necessary oxygen. This often leads to root rot, preventing absorption of water and nutrients, paradoxically mimicking drought. Yellowing from overwatering typically starts with the older, lower leaves, which may also show brown spots or a limp texture.
In contrast, underwatering leads to dehydration, causing the plant to cannibalize nutrients from its oldest leaves to sustain new growth. If the soil becomes excessively dry, the leaves may develop dry, crisp, or brown edges before turning yellow and wilting. Proper care involves allowing the top 50% of the soil to dry out before rewatering thoroughly, ensuring the pot has drainage holes to prevent water accumulation.
Light and Temperature Stress
The placement of the Aglaonema significantly affects its health. While Chinese Evergreens tolerate low light, insufficient exposure can still cause slow, generalized yellowing as the plant conserves energy. Variegated varieties are especially susceptible to losing their color patterns and reverting to a duller green in dimly lit areas.
Conversely, exposure to direct, intense sunlight, particularly from a south-facing window, can scorch the delicate leaf tissue. This damage manifests quickly as pale, bleached-out yellow or white patches that look like burns. Chinese Evergreens are sensitive to sudden temperature shifts, preferring a consistent range between 65 and 80 degrees Fahrenheit. Cold drafts from windows or air conditioning units can cause rapid, widespread yellowing and leaf drop due to thermal shock.
Nutrient Deficiencies and Pests
If environmental factors are ruled out, yellowing may stem from a mineral imbalance or an infestation of sap-sucking insects. Nutrient deficiencies cause chlorosis because elements like nitrogen and magnesium are fundamental building blocks of chlorophyll. Nitrogen is a mobile nutrient, so a deficiency first appears as a uniform yellowing of the older, lower leaves as the plant moves the limited supply to newer growth.
Magnesium deficiency presents as interveinal chlorosis, where the tissue between the leaf veins turns yellow while the veins remain green. These issues are most common in plants that have not been repotted or fertilized in over a year, depleting the soil’s reserves. Pests such as spider mites, mealybugs, and scale insects feed by piercing the leaf tissue and extracting plant sap. This feeding activity leads to a stippled or speckled yellow pattern on the leaves, which can progress to full chlorosis and leaf drop.
Long-Term Care for Healthy Foliage
Preventative maintenance ensures a Chinese Evergreen maintains its lush, green appearance. During the active growing season of spring and summer, feed the plant monthly with a balanced liquid fertilizer to replenish micronutrients. It is also beneficial to flush the soil periodically with plain water until it drains freely, which helps remove accumulated mineral salts that can cause root burn and yellowing.
Chinese Evergreens are slow growers and prefer to be slightly root-bound, so repotting is typically only necessary every two to three years. When repotting, select a container only one to two inches larger in diameter and use a fresh, well-draining potting mix to avoid soil compaction. Regularly wipe the broad leaves with a damp cloth to remove accumulated dust, which blocks light absorption and reduces photosynthesis.