From my perspective as a chrysanthemum, my entire growth strategy is governed by a principle you call "apical dominance." The very tip of each of my stems, the apical meristem, produces a hormone called auxin. This hormone travels down the stem, suppressing the growth of the tiny buds nestled in the leaf axils (the points where leaves meet the stem). My primary instinct is to grow tall and reach for the sun, investing all my energy into that single, dominant terminal bud. This ensures I can compete for light. However, this results in a tall, sometimes leggy plant with all my flowering power concentrated at the top come autumn.
When you "pinch" me—using your fingers or pruners to remove the top inch or two of a stem—you are performing a radical act of communication. You are physically removing the primary source of that suppressing auxin hormone. This action instantly disrupts the hormonal command chain. With the central source of the "stop growing" signal gone, the suppressed lateral buds lower down on the stem are suddenly liberated. They receive the message that the coast is clear and rapidly activate to become new growing points.
The immediate effect of your pinch is that one single stem is now replaced by two, four, or even more new stems emerging from the leaf nodes below the cut. Instead of directing my energy into vertical growth on one stem, I now divert my stored energy and resources into producing multiple new branches. Each of these new branches will, in time, develop its own terminal bud and attempt to re-establish apical dominance. This process, when repeated, fundamentally changes my architecture. I become a denser, bushier, and more structurally robust plant, capable of supporting a greater number of flowers without needing external staking.
It is a common misconception that pinching delays my blooms to an unacceptable degree. While it is true that removing the terminal bud sets back the flowering timeline on that particular stem, the overall calculation benefits us both. A non-pinched mum will indeed flower slightly earlier, but with fewer, potentially top-heavy blooms. By pinching, you force me to create a much larger framework of branches. In the autumn, each of these numerous branches will terminate in a flower bud. The result is not a delay into winter, but a spectacular and prolific display of flowers that completely obscures my foliage, creating the vibrant, dense mound you desire. You trade a few weeks of time for an exponential increase in floral spectacle.
