October 21, 2002
The icy morning whisper of the first frost signals the end of the growing season. Within moments these snowy crystals will melt and evaporate, but the damage has already been done to tender plants whose cell cytoplasm has been ruptured by intercellular water turned to ice. Some plants, like the frosted red clover above, can tolerate temperatures that dip a few degrees below freezing, but this frosty morning was lethal for unprotected tomatoes, corn, and pumpkins. Scientists have observed that the growing season of the northern hemisphere is actually lengthening slightly, but primarily due to earlier spring warming.