From the perspective of the plant itself, the most common reason for green flowers is simply age. The brilliant white "flower" you admire is not actually a flower at all; it is a specialized leaf called a spathe. Its sole purpose is to attract pollinators to the actual flowers, which are the tiny protuberances on the central spike, or spadix. Once the Peace Lily (Spathiphyllum spp.) has completed its reproductive cycle, the spathe's work is done. The plant no longer needs to expend precious energy to maintain its pure white color. As the spathe ages, it often begins to photosynthesize. The green pigment, chlorophyll, develops, allowing the fading spathe to contribute energy back to the plant before it eventually withers and dies. This is a natural and efficient recycling process for the plant.
Your Peace Lily's green spathes can also be a direct physiological response to its lighting environment. In its natural understory habitat, the Peace Lily receives dappled, indirect light. When placed in an environment with very low light levels, the plant adapts. The spathe may produce chlorophyll and turn green to increase its photosynthetic surface area. This is a brilliant survival strategy: if light is scarce, every part of the plant, including the spathe, can be recruited to help produce food (energy) for the entire organism. Conversely, excessive direct sunlight can bleach and damage the spathe, but the more common horticultural issue leading to greenness is consistently insufficient indirect light.
The nutritional status of the plant plays a significant role in the coloration of its structures. An excess of nitrogen, a key macronutrient responsible for promoting vigorous leafy green growth, can directly influence the spathe. High nitrogen levels can signal to the plant to prioritize vegetative growth over reproductive display, encouraging the development of chlorophyll in the spathe and causing it to remain green or turn green more quickly. Furthermore, a general lack of essential micronutrients can stress the plant, potentially disrupting the physiological processes that keep the spathe white. The plant may abort its floral display to conserve resources for basic survival, with a green spathe being an intermediate sign of this shift in priority.
Not all green spathes are a sign of culture or age; sometimes, it is simply a matter of genetics. Through selective breeding, some cultivars of Peace Lily have been developed to produce spathes that are naturally green or have a persistent green hue. Varieties such as 'Sensation' or 'Domino' may exhibit much greener spathes than the common classic white types. For these plants, producing green spathes is their normal, healthy state. It is an inherent trait programmed into their DNA, not a response to their environment or care. Therefore, the green color is a feature, not a flaw, from the plant's point of view.
Temperature fluctuations can interfere with the delicate process of flower formation and pigmentation. The development of a pristine white spathe is a complex biochemical process. If the plant experiences temperatures that are consistently too high or too low during the spathe's development, it can disrupt the expression of pigments (or the lack thereof). This environmental stress can cause the spathe to develop chlorophyll prematurely or fail to lose its green color entirely. The plant interprets extreme temperatures as suboptimal conditions for reproduction and may modify its growth accordingly, resulting in a less showy, greener spathe.
