Extension Notes

Typically, alfalfa needs six weeks of uninterrupted growth before the first hard frost to winterize. The winterization process itself can occur in as little as three weeks, but having a total of six weeks helps to mitigate risks by allowing the alfalfa to move stored reserves to the roots and become acclimated to changing temperatures. By planning on six weeks, we ensure any plants that need longer to winterize have the time to do so, as well as provide insurance against an early frost. The first hard freeze dates for northeast Nebraska fall around the middle of October, so counting back six weeks, final cuttings should be wrapping up soon. Allowing alfalfa to successfully winterize is key to having productive stands next spring and reducing long term losses in your alfalfa stand. Stress during the season also plays a role in the winterization process. Environmental stresses such as drought, heat, hail, or frost cause slower regrowth and shorter stands in season. Even the amount of times we cut stands and the age of the stand are stress considerations. Therefore, if you are trying to push the six-week rule, remember that alfalfa that has been heavily stressed throughout the season or older stands would benefit from having uninterrupted growth to complete the winterization process. When planning your last cutting for older or stressed alfalfa stands, we can use dates for establishing fall alfalfa as a guide to timing a last cutting. While it can vary, for northeast Nebraska, we recommend having fall stands seeded by early September. For the last cutting on a drought-stressed stand, we want to have harvest completed already this year and stands starting to winterize. If we do push the harvest window later, remember that these later harvested fields will have a slow start next year and may have issues overwintering, both of which may impact yield next year.