When is the right time to stop mowing in fall in New Brunswick?

Stop mowing your New Brunswick lawn in October, with your final cut typically falling between October 10-25 depending on your location in the province and that year's weather pattern. The key indicator is when grass growth slows to the point where it's no longer reaching your mowing height between weekly cuts — once the grass isn't growing, there's nothing to cut, and running a mower over dormant turf just compacts the soil.

Grass growth in NB slows dramatically once soil temperatures drop below 10°C and daytime air temperatures consistently stay below 12-15°C. In northern NB around Bathurst and Campbellton (Zone 3b-4a), this typically happens by early October. In the Fredericton area (Zone 4b-5a), mid-October is the usual transition. Coastal areas around Moncton and Saint John (Zone 5a-5b) may see grass still growing into the third week of October due to the moderating influence of the Bay of Fundy and Northumberland Strait.

Your final mow of the season should be shorter than your usual summer height. During summer, best practice is mowing at 3-3.5 inches. For the last cut, lower your mower to 2.5 inches. This shorter height reduces the risk of snow mold, which thrives under long, matted grass — a significant problem in NB's humid Maritime winter conditions. Don't go shorter than 2.5 inches, though, as extremely short grass exposes the crown to direct cold damage and desiccation from winter winds.

Phase the height reduction over your last 2-3 mowing sessions rather than dropping suddenly. If you've been mowing at 3.5 inches all summer, cut at 3 inches two weeks before your final mow, then at 2.5 inches for the last cut. This gradual reduction puts less stress on the grass than a sudden scalping. Each time you lower the height, the grass plant redirects more energy to its roots, which is exactly what it needs heading into an NB winter.

Timing the final mow also matters relative to leaf cleanup and fall fertilization. Ideally, your final mow should happen after your September fall fertilizer has been absorbed and after the main leaf drop has occurred. If leaves are still falling, use your final mowing sessions to mulch-mow them into the turf rather than doing separate leaf removal. This kills two birds with one stone and adds organic matter to the soil heading into winter.

One common mistake NB homeowners make is mowing too late into fall on warm days in November. If you've already done your final mow at 2.5 inches and there's a late warm spell that pushes a bit of growth, leave it alone. Re-mowing disrupts the grass's dormancy preparation and the soil is typically too wet for equipment in November without causing compaction damage. Professional seasonal mowing contracts in NB ($800-2,000) typically include the final cut adjustment and end-of-season timing as part of their service.

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