The short answer: about once a week from mid-May to the end of June, every 7–14 days through summer, and weekly again in September. But Ottawa lawns don't grow at a steady pace, so the right schedule changes through the season.
Most lawns in the city are a mix of Kentucky bluegrass, fescue, and perennial ryegrass. These cool-season grasses grow fastest in cool, wet weather, slow down in the heat of July and August, then surge again when the September rains arrive. Here's how to match your mowing to that cycle.
The one-third rule
Before the calendar, one rule matters more than any other: never cut more than one-third of the grass blade at a time. If your lawn is 4.5 inches tall, cut it to no lower than 3 inches. Removing more than that shocks the plant, weakens the roots, and opens space for weeds.
That rule is exactly why frequency matters. When grass is growing an inch or more a week in late May, waiting two weeks means you either break the one-third rule or leave the lawn looking shaggy.
Month by month in Ottawa
April: the first cut
Wait until the ground is firm. Ottawa's clay soils stay soggy after the thaw, and mowing too early compacts the soil and leaves ruts. A good test: if your footprints stay pressed into the lawn, wait another week. Most years the first cut happens in the last two weeks of April, often after a spring cleanup to clear winter gravel and debris.
May and June: weekly
This is peak growth. Cool nights, warm days, and spring rain mean most Ottawa lawns need cutting every 5–7 days. Skipping a week in early June is how lawns end up clumpy and yellow after the next cut.
July and August: every 7–14 days
In hot, dry stretches, growth slows and the lawn may go partly dormant. Raise your mowing height to around 3–3.5 inches so the blades shade the soil and hold moisture. In dry summers, bi-weekly is often enough; in wet summers, stay weekly.
September: weekly again
Cooler nights and fall rain bring a second growth spurt. September is also when lawns recover from summer stress, so keep cutting regularly and keep the height up.
October: the final cut
As growth slows, your last cut of the year should be slightly shorter, around 2–2.5 inches. Shorter grass is less likely to mat down under the snow, which reduces snow mould in spring. Clear fallen leaves before that final cut so the lawn isn't smothered all winter.
Signs you're not mowing often enough
- Clumps of clippings left on top of the lawn after mowing
- Yellow or brown patches right after a cut (scalping)
- Seed heads appearing on the grass in June
- Weeds filling in thin areas faster than the grass
Weekly or bi-weekly?
For most Ottawa homes, weekly is best in spring and early summer, and bi-weekly can work in mid-summer or on smaller, shaded lawns. We compare the two in detail in Weekly vs Bi-Weekly Lawn Mowing.
Let us keep the schedule for you
AV Group offers weekly and bi-weekly grass cutting plans in Ottawa from May to October (spring cleanups from April), including trimming, edging, and clipping cleanup, plus spring and fall cleanups. We serve Kanata, Barrhaven, Orléans, and neighbourhoods across the city.