Last Mow of the Year: University of Minnesota Advice

University of Minnesota turf specialists give northern homeowners one instruction for the last mow of the year: keep mowing until the grass stops growing. The advice sits in a question-and-answer post on the university’s Turfgrass Science site, dated Sept. 25, 2017. It is older guidance rather than a new announcement, and it stands as the school’s advice for cutting snow mold risk and winter damage.

The same page adds a height rule: a lawn kept above 3 inches in fall should come down to about 3 inches before winter, in several mowings rather than one, so the grass is never scalped in a single pass.

Mow Until Growth Stops, Then Bag the Last Pass

The Q&A says, “Be sure to continue mowing until the grass stops growing, this will help reduce snow molds and winter damage.” It tells homeowners to keep the lawn at its usual fall height if that height is 2.5 to 3 inches. Lawns taller than 3 inches should be lowered to about 3 before winter.

The page lists Dr. Eric Watkins and Dr. Paige Boyle as the contacts for more information. Their titles are not given in the post, and it carries no byline.

It also advises using a bagging attachment on the final mow to take off excess organic matter and leaf litter. That step is aimed at the same snow mold problem, and the school’s newer newsletter, described below, ties leaf litter to it directly.

Why Not Cut It Short

The Minnesota post warns against going too low. Cutting the grass very short, it says, “will be more of a stress to the grass” than the problem the cut is meant to solve. Lowering the height is suggested mainly for lawns that have had snow mold before or that are kept long in fall.

The university’s fine fescue lawn guidance, published by UMN Extension, points the same way for everyday mowing. It recommends mowing above 2 inches, ideally 2.5 to 4 inches, and says not to remove more than a third of the leaf blade in one mowing. For no-mow and reduced-mow fescue lawns, it says a fall mowing is typically recommended to remove dead foliage, reduce snow mold damage and promote spring green-up.

What the Newer Newsletter Says About Snow Mold

The university’s newer lawn-care newsletter gives a slightly lower target. In its November 2023 issue, under the heading “Fall clean-up can reduce snow mold,” it says to consider lowering mowing height by 0.5 to 1.0 inches, to a final height of about 2.0 to 3.0 inches.

That issue also covers leaves. “Mulching or removing excessive leaf litter can also help reduce snow mold pressure,” it says. The research side of the program is working on the problem too: the university’s WinterTurf project tracks the conditions that drive snow mold and studies the pathogens, with a goal of better management strategies and resistant grass varieties.

North Dakota’s Number Is Two Inches

Not every northern extension agent gives the same final height. North Dakota State University Extension agent Don Kinzler recommends lowering the mowing height to about 2 inches to help prevent snow mold, according to a report in The Forum. His timing is “before the first snowfall that sticks around.”

The ranges overlap rather than conflict. Minnesota’s 2017 Q&A puts the ceiling at 3 inches, the 2023 newsletter says 2 to 3 inches, and Kinzler says about 2. Homeowners who have never seen snow mold can stay near the Minnesota range, while lawns that had patches last spring are the ones the advice says to cut lower.

Leaves, Fertilizer and Seeding Dates

Kinzler said raking is not required. He told The Forum that homeowners do not actually have to rake the leaves off the yard, and that leaves can be mulched into the grass with a mower because they supply nutrients. He added a condition: the pieces “shouldn’t lay on the surface, otherwise they should be removed.”

The Minnesota Q&A sets a measurable limit. After mulching, homeowners should still be able to see at least 80 to 90 percent grass. With many trees, the post says, that can mean mulching most leaves and raking up the rest. Closing the mower’s side discharge helps chop leaves finer.

Earlier posts on this site cover the same ground from other sources, including a look at the year’s last mowing height and leaf mulching and a guide to prepping a lawn for winter.

The university’s newsletter archive shows how often the topic returns. Its issue headlines include “Mulch those leaves!” in October 2023 and “Fall tree leaf mulching” in October 2024, and a November 2025 headline asks whether to lower mowing height before winter, according to the newsletter index.

The Minnesota post also draws a line on timing for other fall jobs. Fertilizer is not too late in fall, it says, but should go on by mid-October at the latest. Applications after that can be largely lost to the environment because grass absorbs less in cold weather.

For seeding, the best window in the Twin Cities is mid-August to mid-September, and late September is usually not advised. Dormant seeding, done after soils freeze but before seed germinates, is an option once daytime highs reach 35 to 40 degrees, which usually does not happen until November.

This article was produced with AI assistance and edited for accuracy against the sources linked above.

Image: Shixart1985 – CC BY 2.0/Wikimedia Commons