Calathea plants are a popular choice for indoor greenery, celebrated for their striking, vibrantly patterned foliage. These tropical plants are particular about their environment, often displaying browning leaves as a sign of distress. Understanding the factors that contribute to this browning is the first step toward restoring your Calathea’s lush appearance and ensuring its health.
Understanding Calathea Browning Causes
Humidity Deficiencies
Calatheas originate from the humid understories of tropical rainforests, and they thrive when their environment mimics these conditions. Low ambient humidity in indoor settings is a frequent cause of browning, particularly at the leaf edges, which become crisp. These plants ideally require humidity levels between 50% and 70%, with some varieties preferring even higher.
To counteract dry air, consider placing your Calathea on a pebble tray filled with water, ensuring the pot does not sit directly in the water. Grouping Calatheas with other plants can also create a localized microclimate with increased humidity through transpiration. A small room humidifier is often the most effective method for maintaining consistent humidity levels around your plant. While misting can offer a temporary boost, it often does not provide sufficient long-term humidity and, if done excessively, can sometimes contribute to fungal issues.
Watering Imbalances
Both insufficient and excessive watering can lead to browning leaves on a Calathea. Underwatering causes the plant’s leaves to dry out, often resulting in crispy, brown edges and tips, and sometimes leading to overall wilting or curling. The soil will feel dry to the touch, and the plant may appear droopy. Conversely, overwatering saturates the soil, depriving roots of oxygen and potentially leading to root rot. This can manifest as yellowing leaves that eventually turn brown, often accompanied by a soft or mushy stem.
Calatheas prefer consistently moist soil, similar to a wrung-out sponge, but never waterlogged. It is advisable to water when the top 1 to 2 inches of soil feel dry to the touch. Ensure your plant is in a pot with drainage holes to allow excess water to escape, preventing water from pooling around the roots.
Water Quality Concerns
Calatheas are sensitive to certain minerals and chemicals commonly found in tap water, such as chlorine and fluoride. A buildup of these substances in the soil can cause the leaf tips and edges to burn and turn brown. This browning often appears as distinct brown tips with a yellowish halo.
To avoid this issue, consider using distilled water, rainwater, or filtered water for your Calathea. If using tap water, letting it sit in an open container for at least 24 hours can help dissipate some of the chlorine, though it will not remove fluoride or other dissolved solids. Periodically flushing the soil with pure water can help prevent mineral buildup.
Inappropriate Light Exposure
Calatheas thrive in bright, indirect light, mimicking their natural habitat on the forest floor where they receive dappled sunlight. Direct sun exposure can scorch their delicate leaves, causing brown, crispy patches and fading their vibrant patterns. Leaves may also curl inward as a protective response to intense light.
Insufficient light can also stress the plant and contribute to browning. Place your Calathea near a window that receives bright, indirect light, such as a north or east-facing window. A sheer curtain can diffuse light from brighter windows, protecting the foliage from direct rays.
Temperature Stress
Calatheas prefer stable, warm temperatures, ideally between 65°F and 80°F (18°C and 27°C). They are susceptible to cold drafts and sudden temperature fluctuations, which can lead to browning or curling leaves. Exposure to temperatures below 60°F (15°C) can cause significant stress.
Keep your Calathea away from air conditioning vents, heating ducts, and drafty windows or doors. Maintaining a consistent room temperature helps prevent this type of browning. If indoor temperatures fluctuate, consider moving the plant to a more stable location.
Pest Activity
Pests can also contribute to browning leaves, with spider mites being a common culprit for Calatheas. These tiny arachnids feed on plant sap, causing small yellow or brown spots (stippling) on the leaves, which can eventually merge into larger brown areas. Fine webbing on the undersides of leaves or where leaves meet stems is a telltale sign of a spider mite infestation.
Regularly inspect your Calathea’s leaves, especially the undersides, for any signs of pests. If spider mites are detected, promptly isolate the plant to prevent spread. Treatment often involves thoroughly wiping down leaves with a damp cloth, showering the plant, or applying insecticidal soap or diluted neem oil, ensuring full coverage. Increased humidity can also help deter spider mites, as they thrive in dry conditions.
General Care for Calathea Health
Maintaining a consistent care routine is key to preventing browning and ensuring a Calathea’s overall health. This includes providing consistently moist soil, bright indirect light, a stable warm environment, and regular pest checks. Creating a humid microclimate also contributes to its well-being.
When Browning is Normal
Not all browning on a Calathea indicates a problem; some leaf discoloration is a natural part of the plant’s life cycle. As Calatheas mature, older, lower leaves may naturally yellow and turn brown as the plant redirects energy to new growth. This process is normal and not a cause for concern. These leaves can be pruned away using clean, sharp scissors or shears, helping the plant focus energy on new foliage.