From my perspective as a plant, the primary reason I become leggy is a deep, instinctual need for light. My very survival depends on photosynthesis, the process where I use sunlight to create my food. When I am placed in a spot that doesn't receive enough photons—the energy packets from sunlight—my internal systems sound an alarm. I cannot move my pot, so I must move my body. I begin to direct my growth resources rapidly upwards or towards the nearest, faintest light source. This rapid growth causes my stem to elongate excessively as I desperately stretch my nodes (the points where leaves grow) farther apart in a attempt to find the energy I need to live. It is not a sign of robust health, but rather a survival tactic called etiolation.
This desperate stretch for light comes at a significant cost to my structural integrity. The rapid growth means my stem does not have time to develop the strong, dense tissues I would normally grow in full sun. My stem becomes thin, weak, and pale, unable to properly support the weight of my own leaves, making me prone to bending and breaking. Furthermore, the energy spent on this frantic vertical growth is energy diverted from leaf production. My leaves become smaller, spaced much farther apart, and may lose their vibrant color. The compact, beautiful rosette form that makes me so appealing is sacrificed for a strategy that merely keeps me alive, not thriving.
While insufficient light is the core reason, other environmental factors can exacerbate my leggy growth. The season plays a role. During the shorter days of winter, the intensity and duration of sunlight are naturally reduced. Even in a normally adequate spot, I might not receive my required daily dose of photons, prompting a slower, but still noticeable, stretch. Additionally, temperature interacts with light. In an overly warm environment, especially with low light, my metabolic processes might run slightly faster, accelerating the etiolation process as I grow more quickly with even less light energy to support that growth properly.
My response to low light is a clear demonstration of my priorities. Faced with an energy crisis, I must make difficult choices. I prioritize the growth of stem tissue to seek light over the maintenance of existing leaves or the production of new, healthy ones. The lower, older leaves often suffer the most. I may begin to reabsorb their nutrients and water to fuel the desperate climb towards light, causing them to yellow, wither, and drop. This is why a leggy succulent often has a long, bare stem with a small tuft of leaves only at the very top—it is where my last resources are being concentrated.
