Scarlet pimpernel, commonly known as blue-scarlet pimpernel, red pimpernel, red chickweed, poorman’s barometer, poor man’s weather-glass, shepherd’s weather glass or shepherd’s clock, is a low-growing annual plant. Scarlet pimpernel flowers open only when the sun shines, and even close in overcast conditions. This habit leads to names such as “shepherd’s weather glass”. It has recently started to occur along the verges of salted roads, creating a broad red band along the roadside.
Often this species needs to be planted just before the frost or needs a long period of cold for Stratification, so its seed dormancy can be overcome.