From my perspective as a snowdrop (Galanthus), this is the most crucial factor. We are not like tropical houseplants; we have a deep, innate need for a cold winter. Our bulbs require a prolonged period of cold dormancy, a process you call vernalization, to reset our internal biological clock and initiate the development of our flower embryos. If you purchased me as a potted plant in bloom and then kept me in your consistently warm home, I did not experience this necessary cold period. Without it, my energy will be directed solely towards leaf production, and I will have no impetus to create a flower bud for the next season. I need to experience temperatures between 35-45°F (2-7°C) for a minimum of 10-12 weeks to feel like winter has passed and it's safe to flower.
While I emerge in forests in the wild, it is during a very specific time of year—late winter or early spring—when the deciduous trees above are still bare. This means I am adapted to thrive in the cool weather under bright, but not necessarily direct, sunlight. In your home, if I am placed in a dim corner, I will struggle. My leaves may grow weak and floppy as they stretch desperately for more light. Without sufficient bright, indirect light, I cannot perform photosynthesis efficiently. This means I cannot produce the necessary sugars and starches to build up enough energy within my bulb. Flowering is an energy-intensive process, and if I am light-starved, I simply cannot afford to produce a bloom. I need a bright spot, perhaps near an east-facing window.
My life cycle is opposite to most indoor plants. My active growth period is during the cooler, wetter months. During this time, I prefer my soil to be consistently moist but never waterlogged, which would cause my bulb to rot. However, after my flowering and leaf period concludes, I require a dry summer dormancy. If you continue to water me heavily after my foliage has yellowed and died back, you are drowning me during my rest period and risking bulb rot. Furthermore, I am not a heavy feeder. A balanced, diluted fertilizer applied only once as I begin active growth can be helpful, but too much, especially high-nitrogen fertilizer, will encourage leafy growth at the expense of flowers. My bulb contains all the energy I need for the initial bloom.
I understand the yellowing leaves after blooming may look untidy, but they are my lifeline. After I flower, my leaves continue to absorb sunlight and nutrients for several weeks. This process is how I photosynthesize and recharge my bulb with energy for next year's flower. If you cut these leaves off while they are still green, you are severely depleting my energy reserves. It is like unplugging a battery before it is fully charged. Without this period of energy storage, my bulb will be too weak to produce a flower the following year. Please allow my foliage to die back naturally and completely before removing it.
