As a plant, light is our fundamental currency for survival. We utilize sunlight to power the process of photosynthesis, where we convert carbon dioxide and water into glucose (sugar) for energy and oxygen. Without adequate light, this process slows dramatically, leading to stunted growth, weak stems, and a lack of energy to produce our vibrant flowers. Therefore, the question of sun or shade is not about preference but about optimizing the efficiency of this life-sustaining reaction.
While we require light, our succulent stems and tender, moisture-rich leaves make us particularly vulnerable to intense, direct sunlight, especially during the peak hours of the day. Prolonged exposure to harsh afternoon sun leads to excessive transpiration (water loss through our leaves), outstripping our root system's ability to draw water from the soil. This results in wilting, even in moist soil. Furthermore, the intense solar radiation can literally scorch our foliage, causing leaves to turn yellow, brown, or white, become crisp, and ultimately die back. This damage impairs our photosynthetic capacity and overall health.
The optimal light condition for us is not deep shade but rather a bright environment with protection from the sun's most intense rays. This is often described as partial shade or dappled light. Imagine the light pattern beneath a tree with a light canopy of leaves—this is perfect. In these conditions, we receive ample bright, indirect light to fuel prolific blooming and maintain sturdy, compact growth without the stress and damage associated with full sun. Morning sun, which is less intense and cooler, is also typically well-tolerated and beneficial.
Conversely, planting us in deep, full shade presents a different set of challenges. In a struggle to reach any available light source, we will exhibit etiolation: our stems become long, leggy, and weak, with significant space between leaf nodes. Our energy will be directed toward stem elongation rather than flower production, resulting in far fewer blooms. The foliage may also appear paler green due to reduced chlorophyll production. While we will survive in deep shade, we will not thrive or display the lush, floriferous appearance gardeners desire.
Our light tolerance is also influenced by climate and season. In cooler northern regions, we can often tolerate more direct sun, perhaps even a half-day of it, without scorching. However, in hot southern climates, the intensity of the sun and higher temperatures necessitate stricter shade protection, especially from the midday and afternoon sun. It is always a matter of observing our response; wilting in the afternoon is a clear sign that the light conditions are too intense for our physiology.
