I kept sowing lettuce seeds all July and watching nothing come up: the day I learned what 25°C does to them, I opened my fridge
Lettuce seeds don’t die in July heat—they enter a dormant state called thermoinhibition when temperatures exceed 25°C. Discover why this ancestral survival mechanism sabotages summer sowings and the surprisingly simple refrigerator method that growers use to trick seeds into sprouting on schedule.