Seasonal guide
When to Do the First Mow of Spring in Canada
IllustrationDo the first mow of spring once your grass is actively growing and has reached about 10 to 11 cm (4 to 4.5 inches). The ground should be firm underfoot and the grass should be dry. Rake up leaves and sticks first. Set the mower to 6.5 to 7.5 cm (2.5 to 3 inches) and take off no more than one third. In Canada, that moment comes weeks sooner in Windsor than in Saskatoon.
Why is there no single first mow date for Canada?
Grass doesn't read the calendar. It reads the soil. The Guelph Turfgrass Institute says cool-season grass starts growing once soil reaches 4.5 to 7°C (40 to 45°F). Kentucky bluegrass is one of those cool-season grasses, says K-State Extension.
Soil warms slower than air. A sunny week in March can feel like spring while the ground is still cold and wet. So the first mow follows the soil, not the first warm day.
That's why we won't give you a date. No official source ties a calendar day to that soil trigger. What we can give you is a set of signs that work in any city.
Which parts of Canada wake up first?
Last spring frost dates show which places warm up first. These are Environment Canada climate normals. They're not mow dates. They just show the order.
| City | Normal last spring frost |
|---|---|
| Windsor | April 17 |
| Hamilton | April 29 |
| Kelowna | May 10 |
| Sudbury | May 17 |
| Lethbridge | May 20 |
| Saskatoon | May 21 |
| Moncton | May 22 |
Warm cities like Windsor usually get going weeks before Saskatoon or Moncton. A frosty May morning doesn't mean you skip the mow. It means you wait until the frost melts. Our post on mowing after a frost explains why.
How do you know your lawn is ready for its first cut?
Go outside and check these five things. When all five are true, it's time.
- The grass is green and growing, not just lying flat and brown.
- Most of the lawn is about 10 to 11 cm (4 to 4.5 inches) tall.
- You can walk across it without leaving deep footprints or squishing.
- The blades are dry. No dew, no rain, no frost.
- The leaves, sticks and winter junk are off the lawn.
If the grass is tall but the yard is a swamp, wait. If the yard is dry but the grass is still short, wait. You need both.
How tall should grass be before the first mow?
Use the one-third rule. NDSU Extension says to avoid cutting more than one third of the blade at any time. Cutting too much slows regrowth.
Their example is simple. If you keep your lawn at 7.5 cm (3 inches), cut it before it's more than 11 cm (4.5 inches) tall. The City of Hamilton puts it another way: cut no more than 2.5 cm (1 inch) at a time.
So don't mow the first time the lawn looks a bit shaggy. Let it get to about 10 cm (4 inches). Then take it back down to your normal height.
What if the grass already got too long?
It happens. A rainy April, a busy month, and suddenly the lawn is up past your ankles.
Don't scalp it in one pass. Set the mower high and take off about a third. Wait a few days and cut again, a little lower. Repeat until you're back to your normal height.
Very long grass also clumps when you cut it. NDSU says those clumps can smother the lawn. On that first long cut, bag the clippings or rake up the clumps.
What height should you set the mower to in spring?
Iowa State Extension suggests 6.5 to 7.5 cm (2.5 to 3 inches) for bluegrass lawns in spring and fall. NDSU's range for the whole year is 6.5 to 9 cm (2.5 to 3.5 inches).
Some people cut short in spring to "wake the lawn up." Skip that. A short first cut stresses grass that's just starting to grow. NDSU says it also exposes more soil, which leads to drought stress.
Not sure what your mower deck reads? Measure. Push the mower onto the driveway and put a ruler under the deck. Then you know the real number.
Why should you wait for firm, dry ground?
A mower is heavy. So are you. UConn Extension warns that walking or working on wet soil packs it down. That compaction can hurt plants for the whole season. Their advice is to wait until the soil is drier.
Wet grass is a problem on its own, too. NDSU says to mow when the grass is dry. Dry grass clumps less and mulches into finer bits.
Try the footprint test. Walk across the lowest, shadiest part of the yard. If water pools in your tracks or the ground feels spongy, give it a few more days. Low spots and north sides often stay soggy longest.
What should you do before the first mow?
A mower shouldn't be the first tool on a winter lawn. Clear it first.
- Walk the yard. Pick up sticks, rocks, dog toys and anything the snow hid.
- Rake off old leaves. UConn Extension says leaves left in spring slow green-up and delay growth.
- Check the mower blade. A dull blade makes the first cut look bad.
- Clear the edges along the walk and drive so the trimmer has a clean line.
Our spring yard cleanup checklist walks through the full job, step by step.
What about grey or pink fuzzy patches?
That's often snow mould. The University of Saskatchewan says it shows up after the snow melts. It goes away with warmer, drier weather, and lawns usually recover well. Rake those patches when the lawn is dry. Wear a mask if you're allergic or sensitive. Our partner crews don't spray, and we don't give spray advice.
Why does a sharp blade matter for the first cut?
NDSU says dull blades tear the tips of the grass. Torn tips turn brown. On a lawn that's just greening up, that brown haze is easy to spot. Our post on sharp mower blades covers how to tell if yours needs work.
How often should you mow after the first cut?
More often than you think. Spring is when grass grows fastest. NDSU says you may need to mow every 5 days in spring. St. Albert's grasscycling guide says about every 4 to 5 days in the growing season.
That pace keeps each cut inside the one-third rule. Miss a week in May and you're back to a long, clumpy cut.
You can leave the clippings on the lawn. NDSU says they shade the soil, hold in moisture and recycle nutrients. Just sweep them off the drive and walk. Our post on leaving grass clippings has more.
Can someone else handle the first mow and the rest of the season?
Yes. Golden Oak Lawn Care matches you with a vetted, insured local crew in your city. They do the work. We stand behind it with the Golden Oak Guarantee.
Your crew can start with a spring cleanup to clear the leaves and sticks. Then they roll into regular lawn mowing once the grass is growing. With the Worry-Free Lawn Season, the same crew comes every visit. They text you a photo after every cut. Your first cut is free when you book the season.
We price every lawn by its size from satellite images. Lawn size, how often you want it cut, slopes, gates and obstacles all change the price.
Want it handled? Get your price in 60 minutes, or call 1-866-904-LAWN.
First Mow of Spring Questions
Should I cut my grass short for the first mow of spring?
No. Keep it at about 6.5 to 7.5 cm (2.5 to 3 inches). Take off no more than one third of the blade. A short cut stresses grass that's just starting to grow.
Can I mow if the ground is still soft?
Wait a few more days. Walking or mowing on wet soil packs it down, and that can hurt the lawn all season. Mow when you can cross the yard without sinking in.
Should I bag the clippings on the first cut?
Only if the grass got very long. Long clippings clump and can smother the lawn. On a normal first cut, leave them. They feed the soil.
Is it too early to mow if there's still frost at night?
Not if the grass is growing. Frost can hang on into late May in many cities. Just mow in the afternoon, after the frost has melted and the blades are dry.
Sources: Guelph Turfgrass Institute, K-State Kentucky bluegrass, Environment Canada climate normals, NDSU Extension mowing, Iowa State mowing height, City of Hamilton yard waste, St. Albert grasscycling, UConn soil compaction, UConn leaf management, USask snow mould.
