The beautiful, glossy leaves of the Coffea arabica (Arabian coffee plant) make it a popular indoor houseplant. Originating as an understory shrub in the tropical forests of Ethiopia, this plant has specific care requirements. When these are unmet, the plant often manifests distress through browning foliage. Understanding the location and pattern of the brown spots allows for an accurate diagnosis, helping restore the plant’s vibrant green appearance.
Soil Moisture Problems and Root Health
The most frequent cause of brown leaves relates to the moisture balance in the soil, which directly impacts root function. Brown, crispy leaves browning from the tips and edges inward often point to severe underwatering. When the soil dries out completely, the roots cannot draw up sufficient water, leading to the desiccation and death of the leaf tissue. This drought stress causes the plant to sacrifice older leaves to conserve moisture.
Conversely, entire leaves turning yellow before becoming dark brown and mushy suggests chronic overwatering. Excess moisture in the soil deprives the roots of oxygen, creating an anaerobic environment that leads to root rot, a fungal condition where roots become dark and slimy. Rotted roots are unable to transport water, paradoxically causing the leaves to dry out and turn brown, mimicking the appearance of an underwatered plant.
To prevent this confusion, use a consistent watering schedule, allowing the top two inches of soil to dry out before soaking the plant thoroughly. Use a pot with excellent drainage, ensuring no water sits in the saucer beneath the pot. Additionally, mineral salts in hard tap water can build up in the soil over time, contributing to root stress and leaf burn. This may be mitigated by occasionally flushing the soil or using distilled water.
Managing Humidity and Light Exposure
The coffee plant’s native habitat dictates a strong preference for high atmospheric moisture, making low indoor humidity a common cause of brown leaf tips. When the surrounding air is too dry, particularly during winter or near heating vents, the plant loses moisture faster than its roots can replace it, a process called transpiration. This rapid moisture loss results in the characteristic brown, dry, and crispy margins, especially on newer growth.
To meet the plant’s need for relative humidity levels of 50% or higher, place the pot on a pebble tray filled with water, ensuring the pot does not sit directly in the water. Using a room humidifier or grouping the coffee plant with other foliage plants helps create a localized, moist microclimate. Consistent dry air weakens the plant’s defenses, often leading to infestations of pests like spider mites.
Light exposure is another environmental factor that causes browning, as the coffee plant is naturally an understory dweller. Direct, intense sunlight can lead to leaf scorch, appearing as irregular brown patches or sunburnt spots directly on the leaf surface. The plant thrives in bright, indirect light, so moving it back a few feet from a south or west-facing window, or using a sheer curtain to diffuse the light, can prevent this tissue damage.
Nutrient Buildup and Soil pH
Chemical imbalances in the soil, specifically the accumulation of excess fertilizer salts, can result in a condition known as fertilizer burn. When too much synthetic fertilizer is applied, the high concentration of salts in the soil draws moisture out of the roots via osmosis, damaging the tissue. This damage often presents as brown leaf edges or tips, closely resembling the symptoms of low humidity or underwatering.
To prevent salt accumulation, apply fertilizer only during the active growing season (typically spring and summer) and at a diluted strength. Periodically flushing the soil by slowly pouring a large volume of water through the pot helps dissolve and wash away these excess minerals. The coffee plant prefers a slightly acidic soil pH, ideally between 6.0 and 6.5. A pH that is too high (alkaline) can cause a “nutrient lock-out,” preventing the plant from absorbing essential micronutrients like iron.
Diagnosing Pests and Fungal Infections
If environmental factors are corrected and browning persists, a biological cause, such as pests or disease, may be at fault. Pests like spider mites and scale insects feed by piercing the plant tissue and sucking out the sap. Spider mites, favored by dry conditions, often leave behind fine webbing and tiny yellow or brown stippling spots on the leaves that can eventually coalesce into larger brown patches.
Scale insects appear as small, immobile bumps, typically along the veins or on the undersides of leaves. Their feeding stresses the plant, leading to brown or yellowing foliage. Fungal diseases, such as Brown Eye Spot (Cercospora coffeicola), are another cause, particularly in high-humidity environments with poor air circulation. This infection appears as distinct, circular brown spots often surrounded by a reddish-brown or yellow halo, requiring immediate treatment with a specific fungicide.