When an aloe vera plant changes color from its usual vibrant green to shades of reddish-brown, yellow, or deep orange, it is displaying a common physiological response known as stress coloring. This discoloration signals that the plant is reacting to an imbalance in its environment, which is often mistakenly identified as a disease. The color change is a survival mechanism, indicating the plant is attempting to protect its internal structures from perceived harm. Understanding the specific hue and texture of the browning is the first step toward accurately diagnosing the underlying issue and determining the subsequent action plan.
Environmental Causes: Sunburn or Cold Shock
The most frequent cause of an aloe vera turning a reddish or coppery-brown is overexposure to intense, direct sunlight, especially if the change happens suddenly. This is a form of plant “tanning,” where the plant produces protective pigments to shield its cells from ultraviolet radiation. This protective browning is typically uniform across the most exposed parts of the leaves, which remain firm and plump.
A more serious form of sun damage, true sunburn, appears as bleached, pale, or permanently scarred spots on the leaf surface, indicating that the plant cells have been killed. Unlike stress coloring, these damaged sections will not regain their green color. Cold shock or frost damage presents a different kind of browning, often leading to dark, mushy, or translucent patches on the leaves. Aloe vera is highly sensitive to temperatures below 50 degrees Fahrenheit, and exposure to frost causes the water inside the cells to freeze and rupture the cell walls.
This cold-induced damage results in tissue death, causing the affected areas to turn brown or black and feel soft or slimy to the touch. If the plant is moved abruptly from a low-light indoor setting to a high-light outdoor environment, the sudden, drastic change in ultraviolet intensity almost guarantees this reddish stress coloring will occur.
Diagnosing Issues Related to Watering and Soil
The aloe plant’s health is heavily influenced by soil moisture, which can lead to two opposing forms of browning. Overwatering is the most common issue, causing the leaves to turn yellow or brown, become noticeably soft, and feel mushy, often starting at the base of the plant. This discoloration signals the onset of root rot, where prolonged saturation of the soil deprives the roots of oxygen, causing them to decay.
When the roots rot, they are no longer able to absorb water and nutrients, effectively drowning the plant even though the tissues are waterlogged. The leaves may also appear swollen and translucent due to the excess water pressure, and in severe cases, the entire plant base will feel unstable. A poorly draining soil mix, such as standard potting soil, exacerbates this problem by retaining too much moisture around the roots.
Conversely, browning caused by underwatering is characterized by leaves that are shriveled, thin, and wrinkled, often with dry, brown tips. The plant is drawing moisture from its own reserves to survive, causing the fleshy leaves to collapse. In this scenario, the soil will be completely dry and compacted, often pulling away from the sides of the pot. An overwatered plant has mushy leaves and wet soil, while an underwatered plant has dry, crispy leaves and bone-dry soil.
How to Restore Your Aloe Vera’s Green Color
If the browning is simply stress coloring from too much sun, the plant should be gradually moved to a location that receives bright, indirect sunlight. The plant will naturally reduce its protective pigment production and revert to its healthy green color as it acclimates to the lower light levels. For cold-damaged leaves, the brown, mushy tissue should be removed using a clean, sharp blade, and the plant should be kept in a warmer environment.
If the diagnosis is underwatering, water the plant thoroughly until the water runs freely from the drainage holes, then allow the soil to dry out completely before watering again. This deep watering rehydrates the internal leaf structure, though any tips that have fully dried and browned will likely not recover their green color. A return to a consistent watering schedule where the soil is allowed to fully dry between waterings is necessary for long-term health.
Saving an overwatered plant requires aggressive intervention to address the root rot. The plant should be unpotted immediately, and all soggy, brown, or black roots must be carefully pruned away with sterile scissors. The remaining healthy roots should be allowed to air-dry for several days to promote callousing before repotting into a fresh, fast-draining succulent or cactus soil mix with adequate drainage holes.