Conventional belief: Plants react to weather Alternative view: Plants sense upcoming weather and produce flowers and subsequent fruit accordingly

Plants are traditionally understood to respond to their immediate environment. They sense and react to factors such as:

• : Plants use specialized photoreceptors to detect day length, which helps trigger flowering at the appropriate season12.

• : Plants monitor temperatures to avoid flowering during unfavorable conditions, such as winter (vernalization)3.

• : Changes in humidity lead some plants to close their flowers, often as a strategy to protect reproductive organs from rain45.

• : Certain plants can respond to drops in atmospheric pressure, often closing flowers or pinecones before rain to protect seeds or pollen4675.

Their response mechanisms are chemical and hormonal signals that regulate growth, flowering, and fruiting in direct reaction to environmental stimuli182.

Recent research and long-standing folklore suggest that some plants do more than just react passively—they may anticipate or 'predict' short-term weather changes in sophisticated ways:

• : Some flowers, like dandelions and the scarlet pimpernel, close in advance of impending rain due to their sensitivity to atmospheric changes, especially humidity and pressure4975.

  • Dandelions close their flowers when humidity rises, serving as a reliable rain indicator45.

  • Pinecones close their scales before rainy weather, preventing seed rot45.

  • The scarlet pimpernel is famously known as the "poor man's weather glass" for closing its flowers before rain45.

• : Research on plants like Bulbine frutescens shows that flower buds mature in response to favorable conditions but only open after a lag, effectively "betting" that tomorrow's conditions will match today's, which is advantageous for pollination10. This mechanism works as a form of weather anticipation based on the correlation between present and near-future weather.

Mechanism	What Plants Detect	Typical Plant Response
Barometric pressure	Approaching storms	Flowers/pinecones close69
Humidity	Impending rain	Flowers close, pollen protected45
Temperature	Frost/heat waves	Growth halted or accelerated182
Light intensity	Cloud cover, storm approach	Leaf orientation, flowering12

While plants do not consciously "predict" the weather, they have evolved sophisticated systems to detect subtle environmental changes that precede weather events, thus giving the appearance of anticipation69.
On a biological level, the timing of flowering and fruiting is firmly regulated by a combination of signals involving photoperiod, temperature (including cumulative cold for spring bloomers), and the internal state of plant maturity rather than direct forecasting of distant future weather123.

Plants use environmental cues coinciding with the onset of seasons (e.g., increasing day length, warmth) to initiate flowering and eventually fruiting823.
However, there is no scientific evidence that plants can predict long-term future weather patterns and time flowering months in advance based on upcoming weather. Their responses, instead, are optimized for survival and reproductive success in correlation with environmental patterns that historically align with the seasons823.

Yet, for short-term weather phenomena (such as a storm approaching over several hours or a day), some plants do exhibit anticipatory behaviors that function as natural weather predictors—especially for rain events41095.

:

• Most plants react to current weather stimuli for their flowering and fruiting cycles.

• Some plants anticipate short-term weather changes (mainly within hours to about a day) via sensitivity to atmospheric cues, appearing to "predict" the weather.

• There is no credible evidence for long-term weather prediction by plants leading to coordinated flowering/fruiting, but their evolved sensitivity does allow for reliable, short-term adjustments linked to upcoming weather.

1. https://www.rhs.org.uk/advice/understanding-plants/how-plants-sense-the-environment
2. https://www.cshl.edu/labdish/how-do-plants-know-when-to-flower/
3. https://www.jic.ac.uk/news/a-step-closer-to-understanding-the-switch-that-triggers-flowering-in-plants/
4. https://www.jacksonandperkins.com/blog/outdoor-living-blogs/plants-that-predict-weather/b/plants-that-predict-weather/
5. https://www.farmersalmanac.com/dandelions-and-5-more-plants-that-predict-the-weather
6. https://www.opticweather.com/blog/weather-forecast-nuances-interpretation/can-plants-predict-the-weather-folklore-vs-scientific-observation
7. https://www.gardeningknowhow.com/garden-how-to/info/plants-that-predict-the-weather.htm
8. https://frostygarden.com/2024/06/24/plant-flowering-triggers-why-do-garden-vegetables-flower/
9. https://www.opticweather.com/blog/specific-weather-phenomena-impacts-new/can-plants-predict-weather-folklore-vs-science
10. https://fesummaries.wordpress.com/2023/04/06/flowers-can-predict-tomorrows-weather-matching-pollinator-activity/
11. https://sustainability.stanford.edu/news/know-your-planet-how-do-plants-affect-weather
12. https://www.nps.gov/articles/000/plants-climateimpact.htm
13. https://extension.missouri.edu/news/plants-respond-to-heat-differently-than-humans
14. https://www.youtube.com/watch?v=yBGJMYaw1ZA
15. https://news.climate.columbia.edu/2022/01/27/how-climate-change-will-affect-plants/
16. https://www.nsf.gov/news/scientists-identify-mechanism-responsible-fruit-seed
17. https://www.sciencedaily.com/releases/2024/10/241002154002.htm
18. https://www.lpzoo.org/phenology-and-flowers-researching-the-growing-cycles-of-plants/
19. https://survival-kompass.de/en/weather-forecast-through-nature-observations/
20. https://www.sciencedirect.com/science/article/pii/S1534580722002040