Most forage crops are planted and managed as perennial crops, notes Steve Barnhart, Iowa State University Extension forage agronomist. With careful selection, grass and legume species and varieties can be planted that are capable of surviving normal Iowa winters. However, even with good fertility and fall harvest management or grazing management, some plants, and sometimes even entire stands, can be damaged during the winter.
Late winter and early spring is a good time to evaluate existing hay and pasture stands for winter injury.
You can refer to a previous ICM News article, Evaluating Hay & Pasture Stands for Winter Injury, for guidelines to evaluate stands. In the article, Barnhart discusses in more detail some of the assessment methods you can use.