The Pothos (Epipremnum aureum) is a resilient houseplant known for its cascading vines. Even this forgiving plant signals distress through foliage discoloration. When a leaf turns yellow or brown, it indicates a physiological issue requiring careful diagnosis. Understanding the difference between these symptoms is the first step toward restoring the plant’s vibrant appearance.
Diagnosing Water Stress: Too Much or Too Little
Watering problems are the most frequent cause of both yellowing and browning in Pothos, with the symptoms presenting distinctly depending on whether the plant is over or under-hydrated. When the soil remains consistently saturated, the roots are deprived of the oxygen necessary for respiration, a condition leading to root rot. This root suffocation causes widespread yellowing across the leaves, often starting with the older, lower foliage.
Overwatered leaves may become soft and mushy, and if the condition is advanced, the stems near the soil line will feel soft or exhibit discoloration. Healthy roots should be pale and firm, but root rot causes them to turn black, become mushy, and may emit a foul odor. To correct this, the soil must be allowed to dry completely between waterings, and ensure the pot has adequate drainage holes.
In contrast, prolonged underwatering causes different symptoms. When the plant lacks moisture, it conserves water, resulting in crispy, brown edges and tips on the leaves. This browning is caused by the desiccation and death of leaf cells furthest from the stem.
The plant may also appear wilted or droopy, even if the leaves are dry to the touch. The solution is to thoroughly soak the pot until water drains freely from the bottom, then establish a consistent watering schedule. Waiting until the top two inches of soil are dry or the leaves show a slight droop is an effective hydration method.
Light Exposure: The Role of Sunburn and Shade
The placement of a Pothos significantly influences its health, as light extremes can trigger leaf discoloration. Although Pothos tolerate lower light levels, they thrive best in bright, indirect light. Placing the plant in direct, unfiltered sunlight, particularly from a south or west-facing window, can cause light damage known as sunburn.
Sunburn appears as patches of brown, crispy spots or a bleached, washed-out appearance on the exposed leaf surface. This requires the plant to be moved back several feet or shielded with a sheer curtain to diffuse the harsh rays. Leaves closest to the window are typically the first to show these scorched marks.
Conversely, insufficient light hinders the plant’s ability to photosynthesize effectively, leading to a breakdown of chlorophyll. When kept in a dim location, the leaves often display a generalized pale or yellow hue. If the plant is a variegated variety, low light can cause the white or yellow markings to revert to solid green as the plant attempts to maximize chlorophyll production. Moving the plant to a brighter spot, without direct sun exposure, can help restore its color and vigor.
Secondary Causes: Nutrients, Temperature, and Aging
Once improper watering and lighting are ruled out, other environmental factors can contribute to discoloration. A lack of specific nutrients can cause widespread yellowing, particularly evident with a nitrogen deficiency. Because nitrogen is a mobile nutrient, the plant prioritizes new growth, causing older, lower leaves to turn uniformly yellow as the nutrient is mobilized away.
Mineral salt accumulation, often resulting from excessive fertilizer use or tap water high in dissolved solids, can cause browning that is concentrated at the leaf tips and edges. This fertilizer burn is a form of chemical stress on the roots, which can be remedied by flushing the soil thoroughly with distilled or filtered water. A balanced, diluted fertilizer application during the growing season can prevent both deficiencies and salt buildup.
Pothos are tropical plants that prefer temperatures between 60°F and 85°F, making them susceptible to cold stress. Exposure to sudden temperature drops or cold drafts from windows or air conditioning vents can cause localized cell death. This appears as distinct black or dark brown spots on the leaves, which may also wilt. Moving the plant away from these cold sources prevents further tissue damage.
Not all discoloration signals a problem, as Pothos leaves have a natural lifespan. Senescence means it is normal for a few older leaves, especially those closest to the base of the vine, to turn yellow and eventually drop. If discoloration is isolated to a small number of older leaves, the plant is reallocating resources to support newer growth, and no intervention is required.