First and Last Mow of the Year
There is no date on the calendar for either one. Here is what decides them, and the frost dates that frame the season in your city.
The first and last mow of the year are set by the grass, not the calendar. You start once the lawn is actively growing and the ground is firm enough to walk on, and you stop when it stops growing in fall.
The University of Massachusetts is specific about the end of the season: keep mowing until growth ceases, so the lawn does not go into winter with a tall canopy that mats down under snow.
First and last mow at a glance: First mow: once the grass is growing and the soil is firm and dry enough not to rut. Last mow: keep going until the grass stops growing in fall. Mow at 5–7.5 cm (2–3 inches), higher in shade, and leave the short clippings on the lawn.
Want every job by month? See the Lawn Care Calendar for Canada for the full season.
Season Markers by City
Average frost dates from this site’s frost data. They are not mowing dates; they show roughly when your growing season opens and closes.
| City | Average Last Spring Frost | Average First Fall Frost |
|---|---|---|
| Victoria | Mar 10 | Dec 15 |
| Vancouver | Mar 15 | Nov 30 |
| Kelowna | May 5 | Oct 15 |
| Calgary | May 23 | Sep 21 |
| Edmonton | May 14 | Sep 23 |
| Saskatoon | May 25 | Sep 12 |
| Regina | May 21 | Sep 17 |
| Winnipeg | May 25 | Sep 20 |
| Thunder Bay | May 28 | Sep 20 |
| Sudbury | May 31 | Sep 17 |
| Ottawa | May 9 | Oct 12 |
| Toronto | Apr 20 | Nov 1 |
| Windsor | Apr 20 | Oct 28 |
| Montréal | May 9 | Oct 7 |
| Quebec City | May 17 | Sep 28 |
| Fredericton | May 17 | Sep 26 |
| Halifax | May 10 | Oct 18 |
| Charlottetown | May 10 | Oct 14 |
| St. John’s | May 24 | Oct 13 |
The First Mow
Start when the grass is visibly growing and the soil has dried enough that the mower will not leave ruts or tear wet turf. In spring that is often around the last frost date, earlier on the West Coast and later on the Prairies, but the lawn is the guide. Rake out any snow mould patches first; see snow mould on lawns.
Mowing Height
The University of Massachusetts recommends keeping the grass at 5 to 7.5 cm (2 to 3 inches) with frequent mowing, and leaving the short clippings on the lawn, which return nutrients and help keep thatch down. In shade it recommends mowing higher, 6.5 to 9 cm (2.5 to 3.5 inches), to give the grass more leaf to work with.
The Last Mow
The University of Massachusetts snow mould guidance is to continue mowing until growth ceases, which prevents a tall canopy going into winter. Washington State University gives the same advice: mow regularly until growth stops in fall. In much of Canada that falls a few weeks either side of the first fall frost, but the grass, not the date, is the signal.
A Higher Cut for Prairie Lawns
The University of Saskatchewan recommends a higher blade for Prairie lawns: 8 cm (3 inches) or more, cutting no more than a third of the height at a time with a sharp blade. It notes that lawns cut short lose more water than lawns kept at about 7.5 cm, which matters in a dry Prairie summer.
It also ties fertilizer to the mowing calendar: feed in spring once the grass is actively growing and has been cut at least a couple of times, and do not fertilize in fall on the Prairies or in the far north, because lush grass may not harden off for winter. In fall it suggests mowing the first light leaf drop into the lawn rather than raking it.
Frequently Asked Questions
When should I do the first mow in spring?
Once the grass is actively growing and the soil is firm and dry enough not to rut. The date varies with your city and the spring.
When is the last mow of the year?
When the grass stops growing in fall. The University of Massachusetts says to keep mowing until growth ceases.
How short should I cut grass for winter?
Keep it at your normal height of about 5 to 7.5 cm (2 to 3 inches) and keep mowing until it stops growing, so a tall canopy does not mat down under snow.
What height should I mow my lawn?
The University of Massachusetts recommends 5 to 7.5 cm (2 to 3 inches), and 6.5 to 9 cm (2.5 to 3.5 inches) in shade.
Should I bag grass clippings?
No, leave short clippings on the lawn. They return nutrients and do not cause thatch.
Are frost dates the same as mowing dates?
No. They are season markers. The grass itself tells you when to start and stop.
Sources
- University of Massachusetts Amherst Extension — The Snow Molds
- University of Massachusetts Amherst Extension — What is Thatch?
- University of Massachusetts Amherst Extension — Growing Turf Under Shaded Conditions
- Washington State University Hortsense — Lawn and Turf: Microdochium patch (Pink snow mold)
- Environment and Climate Change Canada — Canadian Climate Normals (the frost dates in the tables, read from this site’s frost data)
- University of Saskatchewan, Gardening at USask — Lawns