On 21 March 2012, the 1st day of spring, the Mississippi River temperature was reported at 61º F. Generally in early spring, the river temperatures will be close to the morning 4-inch depth soil temperature. For your consideration, I have included the data in Table 1 which reflects the average last 32º F temperature in the spring based on 1971–2000 NOAA data.
Table 1 Last 32º F Temperature in the Spring for Iowa____
County Date
Franklin 1 May
Tama 28 April
Scott 22 April
Washington 19 April
Henry 16 April
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Source: NOAA
Table 2 gives you a general guide for starting corn planting. Normally, it is important to know your bare 4-inch depth soil temperature in the morning and the short-term weather forecast for the next 2 to 4 days after planting. But, your soil conditions need to be right.
Table 2 Suggested Planting Date For Iowa______________
Planting Dates________ __
County Normal Earliest Practical
Franklin 25 April 20 April
Scott 20 April 15 April
Washington 15 April 10 April
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Reviewing data from Illinois for the two southern most districts, and having a 3 out of 4 year probability of the last 32º F frost, April 2 and April 3 were reported as the date for that last spring frost.
Today, I would direct my planting activities to seeding alfalfa and sowing grass waterways.