Alfalfa growers should consider the timing of their last cutting to allow for enough re-growth to reduce the risk of winter injury. David Miller, Pioneer alfalfa research director says cutting from September 10 to October 1 in most northern climates rarely allows the crop enough re-growth time. Miller explains that poor fall harvest timing can negatively affect stored root food reserves, which can lead to poor winter survival.
Generally, an alfalfa stand needs about six weeks of re-growth time after the last cutting to gain appropriate nutrients to avoid winterkill. During winter months and the following spring, alfalfa utilizes re-growth nutrients gathered by the roots. Depleting the energy source prior to dormancy will not allow the plant enough energy for adequate spring growth.
For growers who have yet to meet their feed requirement, Miller says growers should wait until two consecutive days of a hard freeze, 24 to 26 degrees. According to the University of Wisconsin, the hardening process in preparation for cold weather begins when temperatures drop below 40 F. This process allows the plant to tolerate freezing temperatures for extended periods.