How Short Is Short Enough Going Into Winter?

The final mow of the year matters more than most people think. Too long, and the grass flops over and mats under the snow. Too short, and you stress the crowns right before winter.

The usual advice

For most cool-season lawns, extension services suggest lowering your final cut by about half an inch to an inch below your summer height. If you've been mowing at 3 to 3.5 inches all season, that puts the last cut at roughly 2 to 2.5 inches.

That's short enough that the grass won't lie down and mat under snow, but tall enough to protect the crown, the growing point at the base of the plant.

Don't do it all at once

Don't drop from 3.5 inches to 2 in one cut. That's scalping, and it shocks the grass. Lower the deck a notch over the last two or three mowings. The rule of thumb still applies: don't remove more than about a third of the blade at a time.

When is the last mow?

When the grass stops growing. Across most of the northern US that's after a few hard frosts, when it's gone a week or two without needing a cut. See when to stop mowing for the season.

Watch the forecast too. Mowing frosted grass damages it; wait until mid-day when the frost is gone.

Why it matters for snow mold

Long, wet grass under snow is the perfect place for snow mold. A shorter lawn dries faster in spring and has less leaf for fungus to grow on. See gray vs. pink snow mold and wet leaves under the first snow.

Grass type matters

• Kentucky bluegrass and perennial rye can handle a slightly lower final cut.
• Tall fescue prefers to stay a bit taller. Don't go below about 2.5 inches.
• Fine fescues in shade are often best left a little taller as well.

Use the last mow to clean up

Run the mower over the leaves with the bagger on. You get the last cut and leaf cleanup in one pass. Then empty the bagger and clean the deck before storing the mower. See mower winter storage.

On golf course roughs and fairways, we lowered the height of cut in steps going into fall. Same idea, same reason: a shorter, upright stand handles snow better.

Sources (2)

University of Minnesota Extension: Late fall lawn care · University of Illinois Extension: Late fall and winter preparation

Photo by fietzfotos on Pixabay.

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