Browning or reddening on an Aloe vera plant signals environmental stress, indicating the plant is attempting to protect itself from unsuitable conditions. This discoloration is the plant’s immediate response to a sudden change in its environment, not a symptom of common pests or diseases. This color change can signify two opposite problems: an excess of sun or an excess of water. Recognizing the specific appearance of the brown color and the leaf texture is the first step in correct diagnosis.
Light Stress and Sunburn
When an Aloe vera is exposed to intense sunlight, it develops stress coloration. This color change is typically a reddish-brown, orange, or bronze hue appearing on the most exposed leaf surfaces. The plant produces pigments, similar to a tan, to shield its cells from ultraviolet radiation and prevent chlorophyll breakdown. This response is noticeable if the plant is moved quickly from a low-light indoor setting to a sunny outdoor spot without acclimatization.
True sunburn, which is damaging, appears as bleached or pale brown spots that feel dry or crispy. While stress coloration is cosmetic and temporary, the physical damage from sunburn is permanent on the affected tissue. To reverse this browning, gradually move the aloe to a location receiving bright, indirect light for the majority of the day. A south-facing window with a sheer curtain often provides the ideal light intensity.
Overwatering and Root Rot
Overwatering is the most frequent cause of browning in Aloe vera, quickly leading to root rot. This browning is distinct, presenting as a dark brown or black color, and the leaves feel soft, mushy, and water-soaked. Decay often starts at the base of the plant where the leaves meet the soil, or it can affect the central, newest leaves first. Excess moisture suffocates the roots by displacing oxygen in the soil, creating an anaerobic environment where fungi and bacteria thrive.
The fix requires removing the plant from its pot to assess the root system. Healthy roots are firm and white or yellow, while rotted roots are black, brown, and brittle or slimy. Use a clean, sharp blade to trim away all affected, mushy roots until only healthy tissue remains. After allowing the trimmed roots to air-dry and callous for a few days, repot the aloe into fresh, sterile, well-draining succulent or cactus soil. The new pot must have at least one drainage hole to prevent water from sitting at the bottom.
Dehydration Stress
Browning resulting from insufficient water is dehydration stress, which looks different from the mushy decay of root rot. The plant consumes moisture stored in its leaves to survive, causing the foliage to become thin, shriveled, and concave. The color change is typically a dull reddish-brown or grayish hue, and the leaves feel tough and wrinkled rather than soft. This indicates the plant’s succulent reserves are being depleted.
To remedy this, the plant needs a deep watering until water flows freely out of the drainage holes. Water the soil directly, avoiding the rosette of leaves at the center of the plant. After this initial soak, place the plant back on a consistent watering schedule, allowing the soil to dry out completely between sessions. Browning that has already occurred at the tips will not revert to green, but the rest of the leaf will rehydrate and plump up.
Recovery and Prevention
Long-term health depends on establishing an environment that mimics the aloe’s native arid habitat, focusing on soil composition and watering habits. A proper growing medium should be a sandy, gritty mix, such as a commercially available cactus or succulent soil, to ensure rapid drainage and aeration. Using a porous pot material like terracotta can help by wicking excess moisture away from the soil and roots.
Establishing a seasonal watering routine is beneficial, as the plant’s needs change throughout the year. In warmer spring and summer months, water approximately every two to three weeks, but reduce this significantly in cooler fall and winter to prevent rot. Maintaining stable temperature conditions is important, as temperatures below 50 degrees Fahrenheit can cause cold damage, which leads to browning. Monitoring soil moisture and providing stable, bright conditions prevents the environmental stress that causes the plant to turn brown.