If frost occurs, wait three to five days to check corn or soybeans for injury.
Frost or freeze damage below the cotyledons often kills soybean seedlings, according to Purdue University. Soybeans are at greater risk to frost damage because the growing point is above ground. If you see firm, white tissue on cotyledons and growing points, the soybean is recovering.
The growing point of corn is underground until leaf four or five—giving the crop some protection from freeze. However, if temperatures are below 28°F for more than just a few hours it can penetrate the soil and cause damage—and it’s more severe if the seedling hasn’t emerged. If the growing point tissue is damaged plants won’t recover.