As a yarrow plant, my primary directive is to survive and reproduce. I send up my flowering stalks to produce seeds, ensuring my genetic legacy continues. Once I successfully set seed, my biological programming tells me my job is done for the season; I begin to divert energy away from new growth and towards hardening off for winter. When you, the gardener, deadhead and prune me, you interrupt this cycle. You trick me into a state of perpetual effort. By removing the spent flower heads, you prevent me from going to seed. My response is not one of defeat, but of determined persistence. I must try again. I will send out new lateral shoots and often a new, though smaller, flush of blooms to achieve my goal. This very act of thwarting my natural cycle is what creates the bushier, more compact form you desire.
In my early spring growth, when my stems are young and tender, you can encourage my bushiness from the start. Before I even think about flowering, if you gently pinch or snip off the top inch or two of my main stems, you are leveraging my innate survival strategy. This simple action, called pinching, removes my apical dominance—the hormonal control exerted by the main, central growing tip. With that tip gone, the growth hormones (auxins) are redistributed. This signals to the dormant buds lower down on my stem that it is their time to awaken and grow. Instead of one single, tall stalk, I will branch out from this point, creating two, three, or even more stems from a single pinch. This results in a denser, more robust clump of foliage and, ultimately, more flower stalks for you to enjoy later in the season.
After my first magnificent display of flat-topped flowers begins to fade, turning brown and crispy, it is time for deadheading. Do not simply snap off the old flower head. For me to redirect my energy most effectively, you should use clean, sharp pruners or scissors. Follow the flower stalk down from the spent bloom until you reach a set of healthy, leafy side shoots or a new, smaller flower bud that may be forming. Make your cut just above this point. This method is far superior to shearing me roughly across the top. A precise cut here does two wonderful things for me: it neatly removes the energy-sink of the dying bloom and simultaneously encourages those lateral shoots you just cut above to develop into new flowering branches. This process can extend my blooming period for many weeks.
Once my flowering efforts are completely finished for the year, usually as autumn approaches, I benefit greatly from a more significant haircut. Cutting my entire plant back to within a few inches of the ground might seem drastic, but it is immensely helpful. It clears away all the tired, potentially mildewed foliage and spent stalks. This clean slate allows all of my energy to be focused on my root system and the crown at my base. I can store nutrients efficiently in my roots over the winter without supporting unnecessary above-ground growth. When spring arrives, I will emerge with vigorous, healthy, and yes, bushier new growth from this strong foundation, ready to begin the cycle again.
