Succulents are known for their tolerance to bright light and arid conditions. Sunburn occurs when these plants receive more solar radiation than their tissues can handle, causing a breakdown in their cellular structure. While succulents require significant light for photosynthesis, an abrupt increase in intensity can quickly overwhelm their natural defenses. Managing light exposure is important, as it prevents permanent scarring and ensures the plant remains healthy and vigorous.
Identifying Sunburn Damage
Sunburn manifests visually as distinct, permanent marks on the fleshy leaves or stems of the plant. A mild burn often appears as bleached white, pale yellow, or light gray patches. These pale spots indicate that the chlorophyll, the pigment responsible for photosynthesis, has been destroyed by excessive radiation.
As the damage becomes more severe, these areas can turn dark brown or black, becoming dry and rough to the touch, sometimes called sun scorch. This darker coloring signifies cell death and tissue necrosis. It is important to distinguish this damage from the natural, vibrant stress colors (red, purple, or orange) succulents develop under high light. Stress coloring is a temporary, protective response where the plant produces anthocyanin pigments, while true sunburn is irreversible tissue damage.
Strategies for Preventing Sunburn
The most effective way to prevent sunburn is through a controlled process of light acclimation. A succulent that has been living indoors or in a shaded area lacks the necessary protective pigments and waxy coatings to withstand sudden, intense, direct sunlight. When moving a plant to a brighter location, the transition should be gradual, typically lasting two to three weeks.
Begin by placing the succulent in a spot that receives bright, indirect light or gentle morning sun for the first few days. Morning light is generally less intense than the harsh afternoon sun. Over the following weeks, slowly increase the duration of direct sun exposure by 30 to 60 minutes every few days. This slow increase allows the plant to naturally build up defenses, minimizing the shock to its system.
Strategic placement is essential, especially during the hottest parts of the year. The intense midday and afternoon sun, particularly between 11 a.m. and 3 p.m., carries the highest risk of damage. If a plant must remain in a full-sun location, consider providing afternoon shade using a structure or a shade cloth. A well-hydrated plant is also slightly more resilient to sun damage, as the turgidity in its cells helps resist heat stress.
Managing Existing Sunburn
Once a succulent has developed a sunburn scar, the damaged tissue will not heal or revert to its original green color. The affected area represents dead cells, meaning the plant must generate new growth to eventually replace the scarred leaves. The immediate action upon discovering a burn is to move the plant out of intense light to a bright, shaded location.
Do not remove the scarred leaves or stems right away, as the damaged tissue offers a protective layer for the healthy tissue beneath it against future light exposure. Severely damaged leaves may dry out and fall off naturally. They can be pruned cosmetically once new, healthy growth appears and the scars become an aesthetic issue.
Long-term care involves allowing the plant to recover by focusing on new growth in its newly adjusted, safer location. Ensure the soil is not waterlogged, as a stressed plant is more susceptible to rot, but do not withhold water to the point of dehydration. The plant will expend energy growing new leaves from its central growth point, a process that can take several weeks or months depending on the species and damage extent.