The best mowing height for every grass type

If you only change one thing about your lawn care this year, make it your mowing height. It costs nothing, takes thirty seconds to adjust, and it does more for the health of your grass than almost anything else you can buy in a bag. Cut too short and you stress the plant, invite weeds, and bake the soil. Get it right and your lawn grows thicker, greener, and far better at shrugging off heat and drought. This guide gives you the ideal mowing height for every common grass type — in both centimetres and inches — plus how to adjust through the seasons and how to actually set your mower.

Why mowing height matters more than you think

Grass isn't just the green bit you see. What happens above the soil and below it are directly linked, and your mower height controls both.

When you leave the grass a little longer, you're really growing a bigger root system. The general rule is that root depth roughly mirrors leaf height: taller blades push roots deeper, and deeper roots reach more water and nutrients. That's why a slightly longer lawn sails through a dry spell while the closely-shaved one next door turns crispy.

Here's what the right height buys you:

• Deeper, stronger roots. More leaf area means more photosynthesis, which the plant invests in roots. Deeper roots mean better access to water and a lawn that recovers faster from stress.
• Natural weed suppression. Longer grass shades the soil surface. Weed seeds — especially crabgrass and other opportunists — need sunlight on bare soil to germinate. Keep the canopy thick and you smother most of them before they start.
• Drought tolerance. Taller grass shades its own roots and the soil, slowing evaporation and keeping the root zone cooler. Your lawn stays green for longer between waterings.
• Fewer diseases and less stress. Scalping rips off too much leaf at once, shocking the plant and leaving wounds for disease to enter.

The key insight: never remove more than one-third of the grass blade in a single mow. This "one-third rule" matters more than any exact target height — chopping a third off at a time keeps the plant feeding itself instead of scrambling to recover.

Recommended mowing heights by grass type

Grasses fall into two broad camps. Warm-season grasses love heat and tend to be cut shorter; they go dormant and brown in cold weather. Cool-season grasses prefer mild temperatures, stay green longer, and generally want to be left taller. Find yours below.

Warm-season grasses

• Bermuda / couch: Loves a low cut and tolerates it well — 1.5–4 cm (0.5–1.5 in). The lower you go, the more often you'll need to mow and the more level your ground needs to be. Most home lawns are happiest around 2.5–3 cm.
• Zoysia: Dense and slow-growing, happy anywhere from 1.5–5 cm (0.5–2 in). A mid setting of around 2.5 cm gives that lush, carpet-like look without demanding a reel mower.
• St Augustine / buffalo: These want to be left long — 6.5–10 cm (2.5–4 in). They have broad leaves and a sprawling habit, and cutting them short thins them out and lets weeds in. Keep them on the taller side, especially in shade.
• Kikuyu: Vigorous and fast, best kept at 2.5–4 cm (1–1.5 in). It grows quickly in warm weather, so expect to mow often to stay ahead of it.

Cool-season grasses

• Kentucky bluegrass: A versatile 4–6.5 cm (1.5–2.5 in). It spreads to fill in gaps, so a medium height keeps it dense and self-repairing.
• Tall fescue: Wants to stay tall at 6.5–9 cm (2.5–3.5 in). Its deep roots make it one of the most drought-tolerant cool-season grasses — don't undo that by scalping it.
• Perennial ryegrass: Comfortable at 4–6.5 cm (1.5–2.5 in). It germinates fast and handles foot traffic well, making it a common pick for family lawns.
• Fine fescue: Best left long at 6.5–10 cm (2.5–4 in). It thrives in shade and poor soil and dislikes being cut short, so a higher setting suits it perfectly.

Adjusting your height through the seasons

The numbers above are starting points, not rigid rules. Your lawn's needs shift with the weather, and a good mower owner moves with them.

• Raise the deck in summer and heat. When it's hot and dry, set your mower to the top of your grass's range — or a notch above it. Taller grass shades the soil, holds moisture, and protects the crown of the plant from heat stress. This is the single most effective thing you can do to keep a lawn green through summer.
• Lower gradually at season transitions. A slightly lower cut in spring (for warm-season grass) or autumn clean-ups helps remove old growth and lets light reach new shoots. Drop one setting at a time over a few mows rather than scalping in one pass.
• Never lower it all at once. Going from a long summer lawn straight to a short cut shocks the plant. Step down gradually, always respecting the one-third rule.
• Leave it slightly longer in shade. Grass in shade gets less light, so give it more leaf area to work with by mowing a little higher than the rest of the lawn.

How to set your mower

Most mowers adjust in fixed steps rather than exact millimetres, so the goal is to get close and check.

• Find the height adjustment lever. On most push and ride-on mowers there's a lever beside each wheel (or one central lever) with notches numbered low to high. Move it to a higher number for a longer cut.
• Measure the actual cut. Park on a flat, hard surface like a driveway. Measure from the ground to the bottom edge of the cutting blade or the mower deck. That's roughly your cutting height — settings labels are often optimistic.
• Check the lawn after mowing. The real test is the grass itself. Measure a few blades after you mow and adjust up or down next time until you hit your target range.
• Keep the blade sharp. A dull blade tears grass rather than slicing it, leaving frayed, whitish tips that brown off and invite disease. Sharpen or replace your blade at least once a season.

Frequently asked questions

What happens if I cut my grass too short?

Scalping removes too much leaf at once, which starves the roots, exposes bare soil to weeds, and dries out the lawn fast. You'll often see a yellow or brown lawn within days, and it can take weeks to recover.

How do I know what type of grass I have?

Look at the leaf width, growth habit, and your climate. Broad-leaved spreading grass in a warm region is likely St Augustine or buffalo; fine, fast-growing grass in a hot area is often couch or kikuyu. If you're unsure, a local nursery or your Lawnova plan can help identify it.

Should I bag the clippings or leave them?

For routine mows that follow the one-third rule, leave them — short clippings break down quickly and return free nutrients to the soil. Bag them only if they're long and clumping, or if the lawn is diseased.

How often should I mow?

Often enough that you never remove more than a third of the blade in one go. In peak growing season that might mean every 4–7 days; in cooler or slower periods, every couple of weeks is plenty.

Is a higher cut always better?

Not always — each grass type has an upper limit, and letting it grow too long can leave it thin, floppy, and prone to matting. Stay within your grass's recommended range and lean higher in heat and shade.

How Lawnova takes the guesswork out of mowing

Knowing the numbers is half the battle — remembering to act on them through a busy season is the other half. Lawnova builds a mowing schedule around your specific grass type, your local climate, and the time of year, then tells you exactly when to mow and what height to set. No more guessing, no more scalped patches, just a clear plan that adjusts as the weather changes.

Get your free Lawnova plan

Mow smarter, not shorter — your lawn will thank you for it.