With temperatures expected to hit the 80s in Iowa today, it might seem that the risk of frost is far behind for this season.
But it’s often prudent to heed the Three Kings frost warning, regardless.
According to the Czech legend, the three kings or saints – Pankrac on May 12, Servac on May 13 and Bonifac on May 14 – were frozen when the temperature dropped while they were fishing at sea. On May 15, St. Zofie came along with a kettle of hot water to thaw out the three frozen kings.
The legend, brought to the United States by Czech immigrants, serves as a warning to protect tender plants against a possible late frost. In Iowa, it’s a good idea to wait until May 15 to plant your tomatoes, peppers and other tender vegetables and flowers, or at least provide them with protection in case overnight temperatures drop below freezing.
Perennials are fine to plant in the ground before the last average frost date; maybe even preferable before the heat of summer hits.
It can also be helpful to know the average last frost date where you live. The National Climatic Data Center provides a chart.