Pothos (Epipremnum aureum) is a popular, resilient houseplant known for its cascading, heart-shaped foliage. Brown spots are a frequent sign of distress, indicating the plant is struggling and requires attention. These spots are not a specific disease but rather a symptom of an underlying issue, ranging from simple care mistakes to biological threats. Understanding the specific appearance and location of the browning is the first step toward successful diagnosis and recovery.
Watering Imbalances and Root Issues
The most frequent cause of brown spots involves improper water management, which directly affects the plant’s root system. Overwatering leads to root rot, where roots sit in saturated soil, suffocating and dying from lack of oxygen. This damage manifests as soft, dark brown, or black spots on the leaves, often starting at the tips or edges.
To confirm root rot, gently unpot the plant to inspect the roots. Healthy Pothos roots are firm and white; rotting roots are dark brown or black, soft, and often emit a foul odor. Correcting overwatering requires allowing the soil to dry out completely between waterings and ensuring the pot has adequate drainage holes.
If the rot is severe, repot into fresh, well-aerated soil. Underwatering results in crispy, dry, light brown patches concentrated on the leaf tips and margins. The soil is typically bone-dry and may pull away from the pot’s sides.
The solution for underwatering is a deep, thorough soak that allows water to drain completely. Establish a consistent watering schedule by waiting until the top one or two inches of soil are dry before watering again.
Pests and Fungal Disease as Causes
Biological agents like pests and fungal diseases cause brown spots through direct damage or infection. Sap-sucking insects, such as spider mites and scale, are common Pothos pests that cause discolored patches where they feed. Spider mite damage appears as fine, pale stippling or tiny yellow spots on the foliage, often accompanied by fine webbing, particularly on the undersides of the leaves.
Scale insects appear as small, stationary, rounded brown bumps on stems and leaves, protected by a waxy coating. Fungal and bacterial diseases, often encouraged by high humidity or standing water on the leaves, can also cause leaf spot. Fungal spots generally appear as small, defined brown or black circles that may be surrounded by a yellow halo.
Bacterial leaf spot often presents as water-soaked lesions that eventually turn dark brown or black. Treatment for pests involves physical removal with a cotton swab dipped in rubbing alcohol for scale, or applying insecticidal soap or neem oil. For fungal issues, immediately remove infected leaves, improve air circulation, and avoid overhead watering to keep the foliage dry.
Environmental Stress and Chemical Burn
Non-biological external factors, including light and temperature extremes, can trigger brown spots. Light burn, or sun scald, occurs when the plant is exposed to direct, intense sunlight, resulting in large, irregular, bleached, dry brown patches on the leaves. Pothos prefers bright, indirect light and should be moved away from unshaded south or west-facing windows to prevent this damage.
Temperature stress, particularly cold exposure, causes cell damage that appears as brown, water-soaked patches that quickly dry and become necrotic. Because Pothos is a tropical plant, temperatures below 60°F can cause stress. Keep the plant away from drafty windows, air conditioning vents, or exterior doors.
A distinct form of browning is chemical or fertilizer burn, which occurs when excess mineral salts from over-fertilization accumulate in the soil. This excess salt draws moisture away from the roots, resulting in a characteristic brown crust or margin along the tips and edges of the leaves. To resolve fertilizer burn, the soil must be thoroughly flushed with clean water, allowing the excess salts to drain completely.