Winter-dormant perennial forage plants remain dormant as long as temperatures in the ‘crown’ area, or upper few inches of the soil, remain between about 0 and 35 degrees F. Snow cover and residual vegetative cover help to insulate the soil and stabilize soil and crown temperatures. Under ideal conditions, as spring temperatures warm through March, the plants ‘break dormancy’ and regrow normally into the spring. Winter injury and winter kill can occur under several conditions: if there is no snow cover and crown temperatures go much below 0 degrees F; when mid-winter ‘warm spells’ cause the plants to ‘break dormancy’ early and are then more susceptible to late-winter cold crown temperatures; and, when plants are submerged in frozen, ponded water in low-lying areas during the winter.
Iowa State University
Barnhart, Stephen K., "Evaluate Forage Stands for Winter Injury" (2013). Integrated Crop Management News. 118.
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