Canadian lawns are watered too often and too lightly. The fix is simple: soak the root zone, then wait until the grass shows it needs more. Summer is short, and a lawn with deep roots handles a July heat wave far better than one sprinkled every evening.
How much water does a lawn need?
About 2.5 cm a week including rain, for a lawn you want to keep green through summer. Split it into one or two soakings so the water reaches 10 to 15 cm down. Sandy soil needs two smaller sessions; heavy clay needs slow watering with a pause so it does not run off the driveway.
When should you water?
Early morning, between about 4 and 9. Less is lost to evaporation, winds are calmer and the blades dry during the day. Evening watering leaves the lawn wet for hours, and that is when leaf spot and brown patch get going in a humid August.
How do you know it is time?
- Footprints stay visible a few minutes after you walk across the lawn.
- The colour turns blue-grey before it goes brown.
- A screwdriver stops short. In moist soil it slides in 10 cm or more.
Should you keep it green or let it go dormant?
Both are fine, as long as you pick one. Kentucky bluegrass is built to go dormant: it browns, stops growing and survives several weeks, then greens up after real rain. What harms it is flip-flopping between soaking and drought.
| Plan | What to do | Trade-off |
|---|---|---|
| Keep it green | 2.5 cm a week in one or two soakings | Water bill, and mowing continues |
| Let it go dormant | About 6 mm every two to three weeks | Brown lawn until rain returns |
Many municipalities also set lawn watering days in summer and tighten them in a drought, so the bylaw may decide for you.
What does the app tell you?
There is no watering reminder in the app. What it gives you is the rain you would otherwise guess at: the weather card shows the chance of rain and the millimetres expected for today and the next two days.
On this day in Toronto no rain was expected for three days, so a lawn under stress would have needed its weekly soaking. When Environment Canada forecasts 10 mm or more, skip a session. The app also estimates soil temperature and warns when it gets warm enough that the lawn needs keeping watered.
In a hot, dry spell it also raises the recommended mowing height, which does more for a stressed lawn than an extra sprinkle. More in How Short to Mow Grass in Canada.
How is new seed different?
New seed needs light, frequent watering: keep the top 2 cm damp once or twice a day until the seedlings are up, then stretch the interval. Timing for seeding is in When to Overseed Your Lawn in Canada. What a Green Lawn keeps the forecast, soil temperature and mowing height together, so you water when the weather calls for it.