Short answer
Set the mower for your grass type, and never cut off more than a third of the blade at once. Keep tall fescue and St. Augustine at about 3 to 4 inches, Kentucky bluegrass at 2.5 to 3.5, and Bermuda and zoysia at 1 to 2. Go a little higher in summer heat and in shade, and keep the blade sharp.
Safety first
Turn the mower off and pull the spark plug wire, or take out the battery, before you measure or touch the blade. Keep kids and pets inside while you mow.
How to set the right mowing height
1Too short? The lawn gets scalped
Cutting too low exposes the stems and the soil. The grass dries out fast, thins and lets weeds move in.
Read all the steps
- Too short? The lawn gets scalped. Cutting too low exposes the stems and the soil. The grass dries out fast, thins and lets weeds move in.
- Know the right height for your grass. Tall fescue and St. Augustine like 3 to 4 inches. Bermuda and zoysia look best at 1 to 2. Taller grass shades the soil and keeps weeds out.
- Measure from the ground to the blade. Park the mower on the driveway, turn it off and measure from the pavement to the bottom of the blade. The numbers on the lever are not inches.
- Never cut off more than a third. If your grass should be 3 inches, mow when it reaches about 4 and a half. If it got very tall, lower it in steps over a few mowings.
- Sharp blade, dry grass, clippings stay. A sharp blade cuts clean instead of tearing the tips. Mow when the grass is dry and leave the clippings: they break down and feed the soil.
- Still not fixed? Call a landscaper Especially if: the lawn stays thin and patchy even at the right height.
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Mowing height by grass type
| Grass | Height |
|---|---|
| Tall fescue | 3 to 4 inches |
| Kentucky bluegrass | 2.5 to 3.5 inches |
| Perennial ryegrass | 2 to 3 inches |
| St. Augustine | 3 to 4 inches |
| Bahia | 3 to 4 inches |
| Centipede | 1.5 to 2 inches |
| Zoysia | 1 to 2 inches |
| Bermuda | 1 to 2 inches |
Typical ranges. Dwarf St. Augustine and hybrid Bermuda can go lower. Go to the top of the range in summer heat and in shade.
What not to do
- Do not scalp the lawn so you can mow less often. It weakens the grass for weeks.
- Do not mow wet grass. It clumps, tears and clogs the mower.
- Do not bag the clippings on a healthy lawn. Short clippings break down in days and do not cause thatch.
- Do not mow in the same pattern every time. Change direction so the grass does not lean and the wheels do not leave ruts.
Is the blade dull?
Look at the tips of the grass a day after you mow. Clean, straight cuts are fine. Ragged, shredded tips that dry out and look frayed mean the blade needs sharpening. Most mowers need it once or twice a season.
When to call a landscaper
- The lawn stays thin and patchy even at the right height.
- The mower cuts unevenly, or the blade is bent or chipped.
- Bumps, holes or surface roots make it hard to mow without scalping.
- You want a weekly mowing service set at the right height.
Frequently asked questions
What is the best height to mow my lawn?
It depends on the grass. Tall fescue and St. Augustine do best at about 3 to 4 inches, Kentucky bluegrass at 2.5 to 3.5, and Bermuda and zoysia at 1 to 2.
Is it better to cut grass short or long?
Longer, within the range for your grass. Taller grass grows deeper roots, holds water better and shades out weed seeds.
What is the one-third rule for mowing?
Never cut off more than a third of the grass height in one mowing. Cutting more shocks the grass and can leave it thin and weak for weeks.
How do I measure my mower height?
Park the mower on a flat driveway, turn it off and disconnect the spark plug wire or the battery. Measure from the pavement to the bottom of the blade. The deck settings are positions, not inches.
Should I mow higher in summer?
Yes. Raising the mower about half an inch in hot, dry weather keeps the soil cooler and helps the grass hold water.
How often should I mow my lawn?
Often enough that you never cut off more than a third at once. In peak season that is about once a week, and sometimes twice for fast-growing Bermuda.