Monstera plants, with their distinctive fenestrated leaves, are popular houseplants. Brown spots on their foliage are a common concern, indicating an underlying issue with the plant’s health or environment. Understanding the causes and how to address them is essential for maintaining a thriving Monstera.
Diagnosing Brown Spots
Identifying the characteristics of brown spots on Monstera leaves is the first step. Note the color (light to dark brown or black), texture (crispy/dry or soft/mushy), and location (edges, tips, center, or entire leaf). Observing the pattern, such as distinct spots or irregular patches, provides further insight into potential causes.
Common Causes and Solutions for Brown Spots
Underwatering
Underwatering causes crispy, dry brown edges or tips as the soil becomes excessively dry, dehydrating leaf tissue. If the soil feels dry several inches down, more consistent watering is needed. Allow the topsoil to dry slightly between thorough waterings.
Overwatering and Root Rot
Dark, mushy brown spots, often with yellowing leaves, signal overwatering or root rot. These spots may appear on older leaves first. Overwatering deprives roots of oxygen, fostering fungal growth, and a foul soil smell also indicates root rot.
To treat, remove the plant, inspect roots for dark, mushy sections, and prune affected parts with sterilized scissors. Repot in fresh, well-draining soil with adequate drainage, then adjust watering to allow more soil drying between waterings.
Low Humidity
Insufficient humidity causes crispy, brown edges that may spread inward. Monsteras are tropical plants preferring high humidity (ideally above 40%). Dry air causes leaves to lose moisture faster than replenished, leading to browning. A humidity meter can confirm this. Increase humidity by placing the plant in a humid room, using a pebble tray, or a humidifier.
Sunburn
Direct, intense sunlight causes bleached, crispy, dry brown spots on Monstera leaves. These irregular spots concentrate on sun-exposed areas. Monsteras naturally grow in dappled light, so direct sun scorches foliage. If symptoms appear, move your plant to bright, indirect light. Sheer curtains can filter strong light.
Pest Infestations
Small, irregular brown spots, sometimes with webbing, sticky residue, or visible insects, suggest a pest infestation. Common culprits like spider mites, thrips, and scale insects feed on plant sap, causing discoloration.
Spider mites leave yellow patches that turn brown. Thrips cause wilting and brown/black spots, often on leaf undersides. Identify the pest and apply appropriate treatment, such as neem oil or insecticidal soap.
Fungal and Bacterial Diseases
Irregular brown spots with yellow halos indicate fungal or bacterial diseases. Fungal leaf spots may appear as light brown, soggy spots. These diseases thrive in overly moist conditions and can spread. To manage, improve air circulation and remove affected leaves with sterilized tools to prevent spread. In severe cases, a houseplant fungicide or bactericide might be necessary.
Nutrient Imbalances
Nutrient imbalances can cause browning, appearing as brown spots with yellowing or stunted growth. Over-fertilization causes chemical burns on roots and brown patches due to salt buildup.
A lack of essential nutrients also causes discoloration. To correct, assess your fertilizing routine, flush the soil with filtered water to remove excess salts, and ensure a balanced nutrient supply.
Temperature Stress
Extreme temperatures cause brown spots. Cold stress leads to dark, mushy spots, while excessive heat results in crispy browning. Rapid temperature fluctuations also stress the plant. Maintain a stable environment; relocate your Monstera if it’s near a drafty window or heat source.
Chemical Burn
Brown spots can appear from residual chemicals (tap water, pesticides) or over-fertilization. Tap water chemicals like chlorine can build up, burning roots and causing crispy brown patches. Excess salt from over-fertilization causes similar symptoms. To remedy, flush the soil thoroughly with filtered or distilled water. Adjust fertilizing and consider filtered water for future watering.
Natural Aging
As Monsteras mature, older, lower leaves naturally yellow and turn brown, indicating the end of their life cycle. This browning is normal and doesn’t signify a health problem. No specific action is required beyond removing senesced leaves for aesthetics.
Physical Damage
Brown spots or tears result from physical damage like bumps, scrapes, or rough handling. Accidental impacts, pets, or strong drafts causing leaves to brush against surfaces can cause localized browning. This damage is typically isolated and does not spread like disease. While no specific treatment exists for the damaged area, preventing future physical trauma is important.
Preventing Future Brown Spots
Maintaining a consistent care routine prevents brown spots. Establish a regular watering schedule based on plant needs, checking soil moisture before each watering.
Ensure bright, indirect light, away from harsh direct sun. Consistent ambient humidity, ideally above 40%, benefits these tropical plants.
Regular pest checks catch infestations early, preventing widespread damage. Good air circulation also deters fungal issues.
Managing Affected Leaves
Once the cause of brown spots is addressed, manage affected leaves. If a leaf is severely damaged, completely brown, or diseased and spreading, pruning is advisable. Use clean, sharp shears to make a clean cut at the base of the leaf stem.
For minor browning, like crispy tips, trim only the brown edges, cutting inside the brown section to prevent further browning. Removing damaged leaves allows the plant to redirect energy to healthy new growth, improving appearance and vigor.