The Aloe vera plant is a resilient succulent, but the vibrant green of its fleshy leaves can sometimes shift to shades of brown, orange, or yellow. This discoloration signals distress, indicating an imbalance in the plant’s environment. Identifying the precise hue and texture of the browning is the first step in diagnosing the underlying problem. These issues are typically rooted in one of three areas: light, water, or temperature.
Light Intensity and Sun Stress
A common reason for Aloe vera turning brown is abrupt or excessive exposure to intense, direct sunlight. This reaction is a photo-protective mechanism known as “sun stress,” not a true sunburn. The plant responds to overwhelming ultraviolet radiation by producing specialized pigments, such as anthocyanins and carotenoids, which act as a natural sunscreen. These compounds mask the green chlorophyll, causing the leaves to display a distinct reddish-brown, bronze, or orange hue.
Sun-stressed leaves maintain a firm, turgid texture, sometimes becoming slightly dry or crispy at the edges. This texture differentiates sun stress from rot. The color change is most often seen when an indoor plant is moved outside suddenly without gradual acclimatization. Prolonged exposure to harsh, unshaded sun can eventually lead to permanent leaf damage and bleached, brittle spots. Moving the plant to bright, indirect light will allow it to stop producing these protective pigments and revert to its natural green color.
The Dangers of Overwatering
The browning caused by overwatering signals a much more serious issue: root rot. When Aloe vera is watered too frequently or planted in poorly draining soil, the roots become deprived of oxygen. This anaerobic environment encourages the growth of fungal pathogens, which attack and decay the root system.
The leaves of an overwatered plant first turn pale yellow, then progress to a dark, often translucent brown or black, starting from the base upward. Unlike sun-stressed leaves, these leaves feel noticeably soft, mushy, and waterlogged to the touch. A foul, sour, or fermented odor emanating from the soil or the plant’s base is a tell-tale sign of advanced root rot. This condition compromises the plant’s ability to absorb water and nutrients, leading to systemic collapse.
Temperature Fluctuations and Cold Shock
Aloe vera is a tropical succulent highly susceptible to damage from low temperatures. The ideal temperature range is generally between 70–80°F, and prolonged exposure below 50°F (10°C) can induce cold shock. If the temperature drops below freezing, the water stored within the leaf cells can freeze and expand, rupturing the cell walls.
This damage appears as dark, water-soaked, or brownish-black patches, often making the affected tissue look glassy or translucent. The browning is localized and permanent on the damaged tissue, which will eventually shrivel and turn black. Even an indoor plant placed too close to a cold windowpane or near a persistent draft can suffer this injury. Immediate relocation away from the cold source is necessary to prevent the damage from spreading.
Restoring Aloe Vera Health
The first step in restoration is to correctly diagnose the cause, as the remedy for each type of browning is distinct.
Addressing Sun Stress
If the plant is suffering from sun stress, immediately move it to a location with bright, indirect light. The healthy green color will gradually return over several weeks as the plant’s pigment levels normalize. Any leaves that are completely dry, brittle, or permanently bleached should be carefully removed using a sterile, sharp blade to redirect the plant’s energy toward new growth.
Treating Root Rot
If the plant is suffering from root rot, it must be unpotted immediately to inspect the roots. Use sterile tools to trim away any roots that are black, slimy, or soft, cutting back to firm, healthy tissue. Allow the entire plant to air-dry in a shaded, well-ventilated area for several days until the cut surfaces have formed a protective callus. Repot the plant in a fresh, well-draining cactus or succulent soil mix, and do not water it for at least a week to encourage new root growth. For long-term prevention, ensure the pot has drainage holes and only water deeply when the soil is completely dry.