When it's 80 degrees on the first day you plant corn and the temperature has been increasing gradually, the warm germination score that you will find on the seed tag on the bag of corn or on the Pro-box of seed corn may be all you need to know.
Typically, warm germination scores run near 95% on quality lots of seed. This means that when the seed lot was tested, 95% of kernels, or 19 out of 20, germinated properly. The test is typically done at a lab that prepares tests for many companies.
Bob Nielsen, Purdue University Extension agronomist and corn specialist in Indiana, recently told Extension educators across the state to advise growers that they may want to know more than just warm germination scores on the seed corn they will be planting this year. Since it looks like soil temperatures may be marginal when some decide to start planting, information on how that seed lot will handle it would be important.
Typically it's reported that soils must be 50 degrees for corn to germinate. That's soil temperature, not air temperature, and that's a minimum, not the preferred temperature for germinating corn.
You can find the warm germination score on the seed tag, Nielsen says. However, most companies do not list the cold germination score. Cold tests are done by exposing seed from the seed lot to cooler conditions in a separate test than what's used to germinate warm germination scores.
Even though the number for a cold score germination test is not on the tag, in many cases the seed company has this information. Nielsen says cold test scores should be 85% or higher.
Ask your seedsman about the cold score for the lot of seed that you have and intend to plant, Nielsen suggests. Just knowing that a hybrid has good vigor or good tolerance to planting early may not be enough. You want to know how the individual lot tested under those conditions in a lab. What matters is getting a handle on how it will perform on your farm.