Summary
For most lawns in Southern Ontario, keep your mower set between 2.5 and 3.5 inches. Taller grass grows deeper roots, handles heat better, and keeps weeds down. The sweet spot is around 3 inches.
Shortcuts
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1. Why Mowing Height Matters
Cutting grass too short stresses it out. Taller grass shades the soil, helping it hold moisture and fight off weeds. It’s a small change that makes a big difference.
2. Recommended Heights by Grass Type
Most Southern Ontario lawns use cool-season grasses. Here’s a quick cheat sheet:
- Kentucky Bluegrass: 2.5–3.5″
- Perennial Ryegrass: 2.5–3″
- Fine Fescue: 2.5–3.5″
3. The 3-Inch Rule: Your Go-To Height
Set your mower deck around 3 inches and you’ll be in the safe zone all season long. It balances appearance, durability, and root health.
4. When to Adjust Your Height (Seasonal Tips)
- Spring: Stick to 2.5–3″ to clean things up.
- Summer: Go up to 3.5″ for heat and drought protection.
- Fall: Back down to 2.5–3″ for a final tidy-up before winter.
- If the conditions are wet, it’s best to raise this by .5″ to keep your grass from clumping.
5. One More Trick: Mow High, Mow Often
Cutting high lets your grass thrive, but only if you don’t let it get too long. Stick to the one-third rule: never cut more than 1/3 of the blade at once.