Fall Alfalfa Harvest Decision Time

We are nearing the end of our “No Cut Window” for alfalfa that typically runs Labor Day through mid-October. This phrase is used because the alfalfa plants are consuming valuable resources to grow when they should be stockpiling them in their roots for the winter. Cutting a stand during this 5 to 6 week period will only further reduce the root reserves and all but guarantee winter injury will occur.

In the Upper Midwest, we have seen an early start to fall with several counties already experiencing frost advisories as temperatures dip into the low 30’s overnight with lower-lying areas gathering that ominous cold white dust. A light frost (29 degrees or higher) will only kill the tops of the plant while the crown will keep growing and continue making fresh forage. A heavy frost (27 degrees or lower for 2 to 4 hours) will signal the crown to cease operations and halt growth.

If you must take this late fall cutting of alfalfa and plan to keep it in rotation next spring, raise your cutter bar height to leave at least three to five inches of stubble. This will allow for a better snow cover and help allow oxygen to get to the stand in areas where ice sheeting occurs. Additionally, harvest before you have too much leaf drop which sacrifices quality.

 Left was NOT cut late last year. Right was cut late fall, exposing stand to winterkill.