How Early Is Too Early to Plant?

Ohio Country-Journal:

With the unseasonably warm temperatures and good field conditions many producers have  considered, or may have already begun, planting corn. Current highs have been reaching into the
80’s and the extended forecast looks favorable, making the thought more tempting. Current soil temperatures
are near 60° F and the favorable temperatures are allowing us to collect as many as 15 growing degree units (GDU) per day. These soil temperatures are high enough to begin germination. Corn requires about 120 GDUs to emerge after planting. If conditions stay similar, as indicated by the forecast, enough GDUs would be collected if corn were planted on March 23 to possibly emerge by March 31. There is considerable risk when planting this early, however. The earliest dates with a 50% or less chance of frost (32°F) range from April 20 for areas immediately adjacent to Lake Erie to May 15 in east central Ohio. A 50% probability of frost (32°F) exists for Bucyrus after April 29, for Hoytville and Newark after May 2, for Warren after May 17, and for Wooster after May 3rd. This leaves a substantial amount of time that frost could have an impact on corn from these early planting dates.  The growing point of a corn plant remains under ground typically until the V5 to V6 growth stage. This helps protect it from damage by frost and may allow it to recover if a frost does occur. However, depending on the severity of a frost, corn can still be impacted. In a study conducted in Wisconsin, plants at the V2 stage of growth were either all cut off at the ground level to simulate a frost that killed the entire above ground portion of the plant, or only half of the plants were cut off to simulate a light frost. When all of the plants were cut off, yield was reduced by 8% and when only half of the plants were cut off yield was reduced, but not significantly. Typically, corn is more likely to recover during earlier stages of growth, but as it matures into later stages, V4 and beyond, there are fewer reserves left in the seed to support re-growth of the plant. The other risk is that if a freeze is severe enough, it could kill the growing point even while still beneath the soil surface.

This year is feeling like it might be one of those years where early planting works out.  With seed costs where they are, I'll be waiting into mid-April to plant.  I don't want to stuff seed into the ground, and then get a hard rain followed by a couple weeks of cold weather.  That's no fun.