From my perspective, rooted here in this spot, I am built to adore the sun. It is my life's engine, fueling the very process that sustains me: photosynthesis. However, like all good things, there is a limit. When the sun's rays become too intense and the heat too oppressive for too long, it ceases to be a source of vitality and becomes a source of stress. My Mediterranean heritage means I am drought-tolerant, but I am not invincible. The intense, direct afternoon sun, especially in peak summer, can overwhelm my systems, leading to a condition you might call sunburn or heat stress.
My leaves are my primary communicators, and they will show you the clearest signs of my distress. Sunburn manifests as physical damage from the ultraviolet radiation. You will notice the leaves that receive the most direct light beginning to change. The most common sign is the development of bleached, pale, or white patches on the upper surfaces. These areas are essentially dead tissue, scorched by the sun. In more severe cases, the leaf edges or entire leaves may turn crispy brown and brittle, crumbling easily to the touch. This damage is irreversible for those specific leaves, as their photosynthetic machinery has been destroyed.
Beyond direct scorching, excessive heat places a tremendous strain on my internal functions. To prevent myself from losing too much water through my leaves (transpiration), I will involuntarily close my stomata (tiny pores). While this conserves water, it also shuts down my ability to "breathe in" carbon dioxide and cool myself, causing my internal temperature to rise. This leads to wilting, where my stems become limp and my leaves droop dramatically, even if the soil is still moist. You may also see signs of leaf curl, where the edges roll inward in a desperate attempt to reduce surface area exposed to the sun. Prolonged heat stress can also cause my normally grey-green leaves to take on a yellowish or reddish hue, a sign of pigment breakdown and overall unhappiness.
If you observe these signs, I am pleading for a change. The most straightforward solution is to reduce my sun exposure. If I am in a container, consider moving me to a location where I receive bright, but indirect light for the hottest part of the afternoon, perhaps with dappled shade. If I am in the ground, a temporary shade cloth during heatwaves can work wonders. Please, check your watering habits. While I dislike wet feet, intense heat increases my water needs. Water me deeply at the base in the early morning, allowing the moisture to reach my roots before the heat of the day causes rapid evaporation. This is far better than a light sprinkle in the evening. Finally, ensure my soil is well-draining; soggy, hot roots are a recipe for further disaster.
