Frost Heave
When the water in soil freezes it causes an upward swelling of the ground which can result in the heaving of recently planted specimens, especially those planted in late fall--therefore unable to develop establishing roots. The roots of these heaved specimens are more exposed and thus more likely to perish. Frost heaving also often ejects signage and moves objects inserted in the ground that are not at or below frost line depth--at least 32 inches in central Indiana and up to 60 inches in some northern counties.