The Ice Saints are named after their patrons. May 11 is St. Mamertus, May 12 is St. Pankratius, May 13 is St. Servatius, May 14 is St. Bonifatius and May 15 is St. Sophie, who also is called by her nickname “Cold Sophie.”
According to folklore, these days were most likely to bring a late frost. In Germany, they were called the “Eismänner”, or Icemen Days, and people believed it was never safe to plant until the Icemen were gone.
This day commemorates St. Sophie who is colloquially known as the 'Cold Sophie' (Die Kalte Sophie). In the old days farmers and wine growers burned wet wood, green twigs and soil, which rose to form a thick smoky fog over the valleys. This fog helped to protect any new growth and blossoms from the frost. The 'Ice Saints' are still widely observed today in the sense that many gardeners and farmers wait until mid May has passed before planting seedlings.