From my perspective, as an Osteospermum, the most common reason I become leggy is a simple, desperate need for more sunlight. I am a sun-loving plant, native to South Africa, and my very existence is fueled by bright, direct light. When I am placed in a location that is too shaded, my internal survival mechanisms kick in. I must find the sun to photosynthesize and thrive. Therefore, I begin to rapidly grow my stems, stretching them out as long as possible in the direction of the nearest light source. This rapid, elongated growth is a stress response called etiolation. My stems become weak and spindly because I am prioritizing height over strength, sacrificing robust leaf production in my quest for the energy I need to survive.
While you might think you are helping me with extra plant food, an overabundance of nitrogen-rich fertilizer can force me into a leggy growth pattern. My systems are designed to use nutrients in balance. An excess of nitrogen sends a powerful signal to my cells to focus almost exclusively on producing green, vegetative growth—specifically, stems and leaves—at an accelerated rate. This can cause me to shoot up quickly without the chance to develop a sturdy, compact structure. The energy is diverted to upward expansion rather than to strengthening my existing form or producing the beautiful flowers you desire.
In my natural state, I am a bushy, spreading plant. A key part of my growth cycle involves being "pinched back" by environmental factors. Without this natural pruning, I tend to send out a few dominant stems that race upwards. When you, my caretaker, do not prune or pinch me, you are missing a crucial opportunity to guide my shape. Pruning directly communicates with my apical meristems (the growing tips). It tells the plant to stop putting all its energy into a single upward point and to instead activate the dormant lateral buds lower down on my stems. This encourages me to become denser and fuller, which is my preferred, healthier form.
To help me return to a strong, bushy form, you must address these issues from my point of view. First and foremost, relocate me to a spot where I can bask in at least 6-8 hours of direct sunlight daily. This is the most critical change; it provides the core energy I need for compact growth.
Next, perform a courageous and strategic pruning. Using clean, sharp shears, cut my longest stems back by one-third to one-half of their length. Make these cuts just above a set of leaves or a leaf node. This action, while it may seem severe, is a clear directive to me. It removes the dominant apical bud, breaking its hormonal control and stimulating those lower lateral buds to wake up and grow into new, bushier branches.
Finally, ensure my nutritional needs are met without being exceeded. Feed me with a balanced, water-soluble fertilizer, but do so sparingly and primarily during my active growing and flowering season. This provides support without forcing unnatural, weak growth.
