Customers shop at a farmers market along the Vltava River in Prague, Czech Republic. The Czech legend of the Three Kings serves as a warning for a late frost. (photo/Cindy Hadish)

Customers shop at a farmers market along the Vltava River in Prague, Czech Republic. The Czech legend of the Three Kings serves as a warning for a late frost. (photo/Cindy Hadish)

A long streak of pleasant weather this month made it particularly tempting for Iowans to start planting their gardens.

This week’s colder-than-average temperatures, however, reinforce why they might have jumped the gun and offer an apt reminder about the legend of the Three Frozen Kings.

Not a spring goes by that I don’t get asked about it, so the story bears repeating. This was told to me several years ago by the late Olga Drahozal of Cedar Rapids.

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.

To find first and last average frost dates where you live, see this chart from the National Climatic Data Center.