When it was sunny and 80 degrees for a brief day or two in April, I heard from several people asking if they should go ahead and plant their gardens. In Iowa, that’s fine for many vegetables, such as cabbage, peas and potatoes, but I warned them to hold off on the tomatoes, cucumbers, squash and other tender plants. Those plants might actually have been OK during the past couple weeks, as it’s stayed fairly warm, so gardeners who took a gamble will be ahead of the game. But old-school gardeners often heed the warning of the Three Kings.
This is something that I ran last year on this blog, but as it’s often asked, here’s what I’ve been told about the legend of the Three Kings:
The Three Kings, or Three Frozen Kings, is a Czech legend that serves as a warning to protect tender plants against a possible late frost. In one of various forms, the story says 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.
Since Czech immigrants found Iowa similar to their home country, those traditions carried over, and, whether or not the story makes sense, it seems sensible in many years to heed the Three Kings warning.
Knowing the last average frost date for your area can also help. That date can vary, however, depending on the source. I’ve seen that in northeast Iowa, the last average frost date is May 10. East-central Iowa is April 30, and southeast Iowa is April 20. Those might seem early in some years, but look accurate for 2009.
A U.S. Climatography report placed northern Iowa, around Decorah, with a last average frost date of May 26; central Iowa, around the Cedar Rapids area, at May 13 and southern Iowa, around Ottumwa, at May 3.
Climatologists say the average can vary, even within the same county. The last frost date might be a week later in low-lying areas or a week earlier on hilltops. Because the frost date is only an average, your safest bet might be to heed the Three Kings warning and wait until May 15 to set out those tender plants.