Plants typically rely on photosynthesis to convert sunlight into the energy they need to grow and thrive. However, in extreme conditions like a nuclear or volcanic winter, where sunlight is significantly diminished, plants can struggle to survive.
Generally, the duration a plant can last without photosynthesis depends on several factors: the plant type, its size, and the stored energy reserves it has accumulated. Most plants can survive for a few days to a couple of weeks without photosynthesis if conditions are right, as they can use the energy stored in their roots and leaves. However, if these conditions persist for an extended period, say several weeks or months, the chances of survival decrease dramatically.
In extreme cases, when sunlight is blocked for prolonged periods, many plants might not survive beyond a few weeks. During a nuclear winter, the fallout could also affect soil quality, water supply, and introduce toxins, which further complicates survival chances. In contrast, some hardy plants or seeds might enter a dormant state, allowing them to wait out unfavorable conditions until sunlight returns. Overall, while some plants have remarkable resilience, sustained absence of photosynthesis can be deadly.