From my perspective as a Black-eyed Susan plant, the most fundamental reason I might not be flowering is simply that I am not yet mature enough. If you started me from seed this season, my primary biological imperative is to establish a strong root system and develop healthy foliage. Flowering and setting seed is an energetically expensive process. It would be a poor survival strategy for me to expend that energy on reproduction before I have secured my own foundation. Most perennial Black-eyed Susans (Rudbeckia fulgida) need a full season of growth to become established before they will reliably bloom, which typically happens in their second year. If I am an annual variety (Rudbeckia hirta), I should flower in my first year, but it will take me several months to reach that stage.
Sunlight is my food. Specifically, it is the fuel I need for photosynthesis, the process that creates the sugars required for all my functions, including the production of flowers. I am a sun-loving plant, evolved for open prairies. To flower prolifically, I need a minimum of six to eight hours of direct, unfiltered sunlight each day. If I am planted in too much shade, my priorities shift from reproduction to survival. I will stretch my stems, becoming "leggy" as I desperately reach for more light. My leaves might be large, but my energy reserves will be too low to initiate flower buds. Without adequate sun, the signal to bloom simply never gets triggered within my cellular structure.
Your intentions are good when you feed me, but the wrong fertilizer can do more harm than good. If you give me a fertilizer with a high nitrogen content (the first number on the package, like 24-8-16), you are essentially telling my system to focus entirely on vegetative growth—leaves and stems. I will respond by producing lush, dark green foliage at the expense of flowers. I am a hardy plant, adapted to soils that are not excessively rich. What I need for flowering is a fertilizer that is higher in phosphorus (the middle number), which promotes bud development. Alternatively, a balanced fertilizer or even no fertilizer at all is often better than an overdose of nitrogen.
My root system is my anchor and my lifeline. If my roots are unhappy, my entire being is stressed, and flowering is one of the first processes to be abandoned. Two common root-related issues are overcrowding and waterlogged soil. If I have been growing in the same spot for several years, I may have formed a dense clump. The center of the clump can become old and woody, competing fiercely with the newer outer shoots for water and nutrients. This internal competition drains energy from the flowering process. Similarly, if I am planted in heavy, poorly draining soil, my roots can suffocate and rot. Healthy roots need oxygen as much as they need water, and without them, I cannot support the demands of a flowering cycle.
You may be trying to help by "deadheading" me (removing spent flowers) to encourage more blooms, which is generally beneficial. However, if you prune my stems back too aggressively or at the wrong time, you might be accidentally removing the very flower buds I was preparing. I form my buds on new growth, but if you cut me back hard in mid-summer, you force me to use energy to regrow stems and leaves instead of developing flowers. Furthermore, if you deadhead too late in the season, you might remove the last buds of the year without giving me time to produce new ones before the growth season ends.
