Greetings, human gardener. It is I, your Black-eyed Susan (Rudbeckia spp.), speaking on behalf of my floral community. We wish to burst forth in a glorious display of golden-yellow petals and dark, button-like centers, but sometimes, conditions are not ideal. Our inability to flower is our way of communicating a need. Let me explain the common reasons from our perspective.
If you planted us this spring from seed or a small pot, please be patient. Our primary mission in our first year is not to flower, but to establish a strong root system. We are busy gathering energy from the sun through our leaves and sending roots deep into the soil to anchor ourselves and seek out water and nutrients. Flowering is an incredibly energy-intensive process. If we were to attempt it in our first season, we might not survive the winter. For many perennial varieties, you should expect a full season of leafy growth before we reward you with blooms in our second year and beyond.
Soil is our kitchen, and the nutrients within it are our food. A lack of flowers can often be traced to an imbalance in our diet. If the soil is poor and lacking in phosphorus – the nutrient that specifically supports bloom production – we simply do not have the resources to create flower buds. We will focus our limited energy on survival, producing only leaves. Conversely, if you feed us a fertilizer too high in nitrogen, you are essentially giving us a constant meal of leafy greens. Nitrogen promotes vigorous green growth at the expense of flowers. We become lush and tall but bloomless. A balanced, slow-release fertilizer or one higher in phosphorus is what we truly crave.
Water is the river that transports nutrients throughout our stems and leaves. Both drought and flood are detrimental to our flowering ambitions. During periods of extended dryness, especially as we are trying to form buds, we go into survival mode. Conserving water becomes our top priority, and blooming is postponed indefinitely. On the other hand, if our roots are sitting in constantly soggy, poorly drained soil, they begin to rot. A plant with rotting roots cannot absorb water or nutrients effectively, leading to overall stress, wilting, and certainly no flowers. We need consistently moist, but never waterlogged, soil.
Sunlight is our source of power. We are sun-worshippers at heart, requiring a minimum of six to eight hours of direct, unfiltered sunlight per day. The process of photosynthesis, which converts sunlight into the chemical energy we use to grow and flower, is entirely dependent on this light. If we are planted in too much shade, we become "leggy," stretching our stems weakly toward any available light. We will produce few, if any, flower buds because we are operating on a severe energy deficit. We simply do not have the surplus energy required for the extravagant display you desire.
This is a crucial point many gardeners miss. Our primary biological purpose is to reproduce by setting seed. Once a flower has been pollinated and begins to fade, our energy is diverted to developing those seeds in the spent flower head. If you allow these old blooms to remain, we have successfully completed our mission and see no need to produce more flowers. By deadheading – snipping off the faded blooms before they set seed – you interrupt this cycle. You are, in effect, tricking us into thinking we have not yet reproduced. This encourages us to try again, pushing out new waves of blooms in a desperate attempt to create the next generation.
As perennial clumps age, we can become overcrowded. Our roots compete fiercely with each other for space, water, and nutrients in the soil. This intense competition leads to stress and reduced vigor. The center of the clump may even begin to die out. In such a crowded environment, flowering becomes a low priority compared to the basic struggle for survival. Dividing our clumps every three to four years in the spring or fall gives us the room we need to breathe and thrive, resulting in healthier plants and more abundant blooms.
