When to plant corn

We are all getting a little antsy to be in the field.  We would like to know we could start on corn soon.  The question this year is about the cold soils.  We know people have had success in the past planting to cold soils, but how cold?  We had frozen soil 2 days ago.  Not just freezing temperatures.  It is still early.  In our area, soil moisture is about right for planting. Usually that is a good reason to start.  Cool weather is probably pushing the ideal date a little later already.  If you put corn into the ground before soil temperature is 50 Degrees F, it will not germinate.  The question is, will the seed rot?  Probably not, but why take a chance?  Seed treatments help and soils will warm up sometime.  Warm wet soils seem to damage seed more than coll soils.  In our area, there comes a time, sometime around April 10, that you know soils will warm up and if moisture conditions are good, there will be little yield cost for planting.