Why Are My Calathea Leaves Turning Yellow?
Understand what your Calathea's yellow leaves are trying to tell you. This guide helps you identify the root cause and restore your plant's ideal conditions.
Yellowing leaves on a Calathea are not a sign of failure but a signal that an aspect of their environment needs adjustment. These plants are known for their striking foliage, and a change in leaf color is a direct communication of stress. Understanding these signals is the first step toward diagnosing the issue and restoring the plant’s health.
Common Causes of Yellowing Leaves
Watering imbalances are the most frequent cause of yellowing leaves on a Calathea. Overwatering leads to soggy soil, depriving the roots of oxygen and causing root rot. When roots become mushy and unable to absorb nutrients, the leaves turn yellow and may feel limp.
Conversely, underwatering stresses the plant, causing leaves to develop crispy, brown edges that are often preceded by yellowing. You can differentiate the two by checking the soil. If the top few inches are constantly wet it is likely overwatering, whereas bone-dry soil indicates the plant needs more moisture.
Calatheas originate from tropical rainforests and are adapted to high humidity. In many homes, the air is too dry, especially during winter when heating systems are active. This lack of moisture causes brown, crispy leaf edges, which can be followed by the entire leaf turning yellow. The plant loses water through its leaves faster than its roots can absorb it, causing the tissue to dry out.
The amount of light a Calathea receives directly impacts its health. These plants thrive in bright, indirect light that mimics the dappled sunlight of a jungle canopy. Direct, intense sunlight will scorch the leaves, causing them to look faded or yellow. Insufficient light is also problematic, as the plant cannot photosynthesize effectively, leading to pale, yellowing leaves from a lack of chlorophyll.
Calatheas are sensitive to minerals and chemicals in tap water, such as chlorine and fluoride. These substances can accumulate in the soil, becoming toxic to the plant. This damage often appears first as yellow or brown leaf tips and margins. The discoloration then spreads inward as the plant continues to absorb the substances.
A nutrient imbalance can lead to discolored foliage. An under-fertilized Calathea may develop a uniform yellowing across older, lower leaves. Over-fertilizing is just as damaging, as excess fertilizer salts in the soil can burn the roots. Damaged roots cannot function correctly, which causes the leaves to yellow.
Pests like spider mites are a frequent challenge for Calatheas. These tiny arachnids are hard to see but leave behind fine, silky webbing on the undersides of leaves. They feed by piercing the plant’s cells to suck out the contents. This creates a pattern of tiny yellow or white dots called stippling and can cause the entire leaf to turn yellow.
As a Calathea produces new foliage, it is normal for the oldest leaves at the bottom of the plant to turn yellow and fall off. This is the plant’s way of redirecting energy toward new growth. If only one or two lower leaves are yellowing and the rest of the plant appears healthy, it is a natural process.
How to Treat Yellow Calathea Leaves
A Calathea leaf that has turned yellow will not revert to green. The plant has already started to seal off the leaf to conserve resources, so the best action is to remove the affected foliage. Pruning redirects the plant’s energy from a dying leaf toward developing new, vibrant leaves.
To remove yellow leaves, use clean, sharp scissors or pruning shears sterilized with rubbing alcohol to prevent introducing pathogens. Follow the leaf’s stalk, or petiole, down to the base of the plant. Make the cut as close to the main stem or soil line as possible without damaging surrounding stems.
Removing dying foliage also increases air circulation around the plant’s base, which helps prevent fungal issues that thrive in damp conditions. Old and decaying leaves can also harbor pests. Promptly removing them eliminates potential habitats for unwanted insects and contributes to the plant’s overall health.
Preventing Yellow Leaves on Your Calathea
To prevent yellow leaves, establish a consistent care routine. The goal for watering is to maintain evenly moist soil without it becoming waterlogged. A reliable method is to check the top one to two inches of soil with your finger. If it feels dry, it is time to water.
Position your plant in a location where it will receive bright but indirect sunlight for most of the day. An east-facing window with gentle morning sun is a good choice. A spot a few feet back from a south or west-facing window also works well, or you can use sheer curtains to diffuse direct sunlight.
High humidity is necessary for Calathea care. You can increase moisture in the air by grouping it with other plants to create a humid microclimate. Another method is placing the pot on a tray filled with pebbles and water to allow for gradual evaporation. Using a small humidifier near your Calathea is also a highly effective solution.
Avoid using tap water directly, especially if your water is hard or heavily treated. Using filtered, distilled, or rainwater for your Calathea prevents the buildup of minerals in the soil that leads to yellowing. If you must use tap water, let it sit out for at least 24 hours to allow some chlorine to dissipate.
During the growing season of spring and summer, use a balanced liquid fertilizer about once a month. Dilute the fertilizer to half or a quarter of the recommended strength to avoid fertilizer burn. In the fall and winter, when the plant’s growth slows, reduce or stop fertilizing to prevent unused nutrient salts from accumulating in the soil.