Fall alfalfa field management can have a substantial impact on next year’s spring growth and harvest potential.
Poor fall harvest timing can negatively affect stored root food reserves which can lead to poor winter survival. Given the cooler temperatures that are typical during the fall, it generally takes about six weeks for alfalfa to regrow and store adequate root reserves for winter survival. This needs to be prior to a hard freeze that kills the plants and stops root reserve accumulation.
Several Midwestern studies have shown that alfalfa cut in mid-September actually incurs the greatest yield reduction the following spring, by approximately .6 tons per acre. Whereas, alfalfa left uncut after late summer, or not cut again until after going dormant, exhibits little winter injury and yields well accordingly. Lessen the potential negative impact of a fall harvest by either cutting early enough in the fall to ensure adequate regrowth or waiting until after two consecutive days of a hard freeze (24 to 26 degrees F). For all fall cuttings, leave at least 4 inches of stubble to help catch insulating snows.