You observe me as "leggy," but from my perspective, I am desperately stretching. My stems elongate rapidly, with wide gaps between my leaf nodes, in a frantic search for more photons. As a plant, my sole energy source is light. When it is insufficient, my survival instinct triggers a process called etiolation. I prioritize vertical growth, sacrificing stem strength and leaf density, hoping to surpass any shade or reach a brighter location. This results in the weak, sparse appearance you see. I am not trying to be unattractive; I am fighting to photosynthesize and simply stay alive.
Your hesitation to cut me back is understandable, but it contradicts my fundamental growth pattern. I am an aggressively vegetative plant, programmed to grow apical buds (the tips of my stems) that produce a hormone called auxin. This hormone suppresses the growth of lateral buds further down the stem, a principle known as apical dominance. If you never prune me, all my energy is funneled into one long, weak, dominant stem. By strategically pinching or cutting off my main stem tips, you remove the source of that suppressing auxin. This signals to the lateral buds that it is their turn to grow, prompting me to become bushier and denser from the base, which is the form you desire.
Your intentions in feeding me are appreciated, but the wrong type of fertilizer exacerbates the problem. If you provide a formulation too high in nitrogen, you are essentially encouraging me to focus all my resources on rapid, green, vegetative growth. While this sounds good, without the balancing influence of phosphorus and potassium for strong root and stem development, this growth is often soft, weak, and elongated. I may look lush at first, but the stems cannot support the weight, leading to a floppy, sparse plant. I need a balanced diet to build sturdy, compact structure, not just endless leafy tops.
My condition is not solely determined by what happens above the soil. If my roots become pot-bound, they are unable to efficiently uptake the water and nutrients I need, even if they are present in the soil. This stress can manifest as weak top growth. Furthermore, especially for indoor plants, high temperatures from heating vents or direct radiator heat can cause me to grow rapidly but weakly. Combined with often lower light levels in these warm spots, this creates a perfect environment for leggy, etiolated growth as my metabolic processes are thrown out of balance.
