MANHATTAN, Kan -- If producers haven’t done so already, they may have missed the best timing for the year’s last cutting of alfalfa, according to Kansas State University agronomist Jim Shroyer

“Depending on the weather in October, producers can be tempted to make one last cutting in fall before the first killing freeze. Often, though, that’s not a good idea. The timing of the last cutting can have a long-lasting impact on the productivity of the stand,” said Shroyer, who is a crop production specialist with K-State Research and Extension.

At this stage of the growing season, alfalfa plants need to store enough carbohydrates to survive the winter, Shroyer explained. So, even if significant growth has occurred, a last cutting in mid-October could reduce root reserves during a critical time

If root reserves are not replenished adequately before fall’s first killing freeze (24 to 26 degrees), the stand will be more susceptible than usual to winter damage, he said. That, in turn, could result in slower greenup and early growth next spring.

Shroyer recommends timing the last cutting before fall dormancy so the crop has 4 to 6 weeks of growth time (i.e., for 8 to 12 inches of foliage) before the average first killing-freeze date. That should allow adequate time for restoring root reserves.

“About the worst thing that could happen to an alfalfa stand that’s cut in mid-October would be for the plants to regrow about 3 to 6 inches and then get a killing frost. In that scenario, the root carbohydrate reserves would be at a low point, and that certainly could hamper greenup next spring,” Shroyer said.

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