From my perspective as a Greek oregano plant, sunlight is my primary source of energy. I use it, along with carbon dioxide and water, to create the sugars that fuel my growth and produce the potent aromatic oils you love. I am a Mediterranean native, which means I am inherently a sun-worshipper and crave several hours of direct, bright light each day to thrive. However, like all good things, there is a limit. When the intensity and duration of sunlight exceed my metabolic capabilities and my ability to manage water loss, I begin to show clear signs of distress. It is not merely a matter of being "hot"; it is a physiological crisis of energy and hydration.
The most immediate and visually obvious sign I display when receiving too much sun is a change in my leaf color. This is not the beautiful purple or bronze tint I sometimes get with cool weather; this is damage. You may notice the edges of my leaves turning brown, crispy, and brittle—this is classic leaf scorch. It occurs when the rate of water loss from my leaves (through transpiration) exceeds the rate at which my roots can absorb it from the soil. The leaf tissue literally dies from dehydration. Alternatively, you might see my vibrant green leaves start to look pale, washed-out, or even yellowish-white. This is called bleaching or sunscald, where the intense ultraviolet radiation breaks down my chlorophyll, the pigment essential for photosynthesis. Without it, I cannot effectively produce food.
Please touch my leaves. A healthy Greek oregano plant should have leaves that are somewhat leathery and resilient, a natural adaptation to sunny, dry climates. When I am overwhelmed by sun, this texture changes drastically. My leaves may become overly dry, papery, and brittle to the touch, crinkling at the edges before the browning even sets in. In a desperate attempt to conserve water, I might also curl my leaves inward. By reducing the surface area exposed to the harsh sun, I slow down the rate of transpiration. This is a clear, physical cry for help, indicating that I am trying to protect myself from excessive water loss.
While I am struggling to survive under the intense sun, my growth patterns will be severely affected. You might notice that my new growth appears stunted, with smaller leaves and shorter internodes (the spaces between leaves on the stem) as I conserve energy. Conversely, and somewhat paradoxically, I might also become "leggy." If I am in a spot with extreme heat and light but also competing with other plants or structures, I might stretch spindly stems in a frantic, weak attempt to find a more favorable light condition. This growth will be feeble and lack the robust, bushy form I am known for.
My distress is often a combination of too much sun and an incompatible watering routine. If the sun is baking the soil around my roots all day, it can cause the soil to dry out with extreme speed and ferocity. Even if you water me regularly, the water may evaporate before my roots can drink their fill, or it may only wet the very surface. This creates a cycle of drought stress that exacerbates the sun damage. Furthermore, hot soil can actually heat the water in it, making it less available for my root system to uptake, leaving me parched even when moisture is technically present.
