What Is the Best Height To Cut Grass?

There is no one-size-fits-all ideal grass cutting height. The best height to cut grass depends on the type of grass, location, and the environment. Cutting grass regularly to the recommended heights promotes deep, healthy root systems. Strong root systems are more drought and flood-resistant.

Our grass cutting height chart provides information on the most popular types of grass, the best heights to cut at, and the grass height after cutting.

Popular Types Of Lawn Grass

Lawn grasses are developed to meet different conditions. Drought resistance, wet conditions, frost, snow, and heat. Many grass varieties are native to certain locales and environments, but hybridization allows them to be used for lawns in wider areas.

Warm-Season Grass

Warm-season grass can be cut at lower heights than cool-season grass. 1 ½” to 2” is common. Individual grass types have slightly different requirements. Warm-season grasses have consistent growing habits. It is easy to plan when and how to mow them.

The most popular warm-season grass types are:

• Zoysia Grass
• St. Augustine’s Grass
• Tall Fescue
• Centipede Grass
• Bermuda Grass

Cool-Season Grass

Cool-season grasses grow quickly in the spring and fall, but slow down in the heat of summer. Adjust your mowing habits and/or mower deck height to account for the time of year to avoid damaging the lawn.

Cool-season grasses include:

• Fescue
• Ryegrass
• Kentucky Bluegrass

Grass Cutting Height Chart

The following chart lists the most common types of grass grown in the USA. All of the heights after cutting closely follow the “one-third rule” to provide optimum grass health.

The One-Third Rule

Following the one-third rule when cutting grass usually gives you a healthy, strong, and vibrant lawn. It is simple and easy to follow. Only cut off one-third of the grass height at a time, regardless of how long it is.

The chart above shows the ideal height to cut your grass, but often environmental conditions or other circumstances prevent mowing at the proper time, and the grass gets too long. The natural inclination is to leave the mower set at the normal cut height and mow it in one pass.

Don’t, if you want a healthy, strong lawn. Cutting more than one-third off the grass height at one time stresses the grass. It is more susceptible to disease, pest infestations, and drought.

Cutting off too much of the grass blade reduces the sunlight-capturing area and slows photosynthesis. The plant has to draw on nutrients from the root system to repair damaged blades, creating a weaker plant. The grass may stop growing its root system completely to put its energy into repairing the overcutting damage, and into growing new blades and stems. 

Regardless of the existing grass height, always measure it in a few locations, calculate one-third of the length, and only cut off that much. If you need to remove more to achieve the recommended height, wait a few days, measure, and cut it again.

Leave Grass Longer In the Summer

Consider the heights on the growth chart as targets for optimal conditions. Environmental conditions like too much or too little rainfall, heat, and the amount of watering your lawn receives should be considered when cutting grass.

Hot, dry summer weather damages root systems. Leaving the grass longer protects the roots by providing shade. Plan to leave the grass length at the taller heights recommended in the chart. If the forecast is for a long, hot spell, you can even leave the grass a bit longer. 

When the weather moderates, start cutting the grass back to your preferred height. Don’t whack it all off at once. Use the “one-third rule” to prevent damage.

Cut Grass Lower Before Winter

Cooler fall days with less sunlight slow grass growth. Make sure your lawn is prepared for winter by cutting it shorter. Two inches is about right. Long enough to prevent winter damage to the roots, but short enough to allow easy leaf removal. 

Longer grass blades left over winter and under the snow get packed down and create a mat that is a perfect breeding ground for snow mold and other diseases. Long over-winter grass is more difficult to remove in spring and slows vigorous spring growth.

Further reading: Compelte Winter Lawn Care

Fertilizing and Over-Seeding

Granular fertilizer and new grass seeds are only effective when they fall through the grass and reach the ground. Cut grass to the lower recommended heights before fertilizing, overseeding, or applying pest and disease control. 

Longer grass blades hold all but liquid products off the ground. Making for a waste of time and money. 

How Often Should Grass Be Cut?

Cutting grass is not everyone’s idea of a good time. It is tempting to cut the grass short to extend the time between cuts. Lawns cut short look neat and well-kept. But resist the temptation to cut your grass short.

Grass cut too short often leads to disease, die-off, increased weed growth, and pest infestations. Shorter grass blades mean less leaf area to absorb sunshine and grow strong, healthy root systems.

Most lawns are mowed using push mowers, but robot mowers like the Navimow are becoming more popular for precise lawn care. Traditional mowers require manual height adjustment and the effort of pushing them around. Riding mowers are heavy, can leave ruts in your lawn, and are impractical for smaller areas. Finding time to cut your grass by one-third can be a problem due to weather and time constraints.

The Navimow i105 is completely programmable. Set the height and tell it to mow when the grass needs cutting. This robot mower keeps your grass at the optimum height for a healthy lawn without the stress of having to find the time and energy to push a mower around.

Lawnmower Height Settings

Newer push lawnmowers usually have one lever to adjust the mowing height. Some have one lever per wheel. If you don’t trust the depth settings marked on the levers, turn the mower on its side, hold a board across two wheels, and measure the actual blade depth before cutting to ensure accuracy.

Always opt for higher lawnmower settings. You may have to cut the lawn a little more often, but cutting off less reduces stress and damage to grass plants.

More importantly, keep your lawnmower blades sharp. Even if they require attention two or three times during mowing season. Dull mower blades leave torn, ragged grass that is more susceptible to disease. The cut ends also take longer to heal.

Grass Cutting Height and Grass Clippings

Grass clippings left on the lawn after each cutting sink to the base of the blades and replace soil nitrogen. Leaving the clippings on the lawn after each mowing eliminates one fertilizer application each year. 

This is only an effective strategy if you mow regularly and follow the one-third rule. Cutting two inches off a thick, healthy lawn in one pass leaves swathes of grass that do not sink down to the soil level and decompose. If the grass clippings are too thick, they turn grass brown because it prevents sunlight from getting to the growing blades.

Use a mulching blade on your mower to produce even shorter clippings. They settle to soil level more easily and decompose faster. If you have to remove grass clippings, they are a great additive to compost. 

Note: Leaving grass clippings on lawns usually does not cause a thatch problem. Adhering to the one-third rule should prevent the necessity of dethatching your lawn.

Identifying Your Lawn Grass

Unless you seeded the lawn, it can be difficult to identify the type of grass that makes up your lawn. This map identifies the zones where different types of grass grow best. People living in the transition zone successfully grow most types of grass.

Lawns look identical to most people, but grass species have distinct physical characteristics. Look closely at your grass to observe color, texture, appearance, and growth patterns. If you are still not certain, contact your state department of extension. Take them a sample of the grass if you can, or sending a sharp, clear picture may be enough to get the information you need.

Knowing your lawn’s grass species is the important first step when deciding the ideal grass cutting height. What to look for:

• Zoysia Grass. Carpet-like growth. Thick, stiff blades with hairy edges. Pointed tip. Dark green.
• St. Augustine’s Grass. Thick matted growth. Broad, flat blades. Course, rough texture. Medium to Dark green.
• Tall Fescue. Upright clumps of narrow blades with rough edges. Dark green.
• Centipede Grass. Creeping growth. Coarse-textured blades. Light green.
• Bermuda Grass. Thick, dense runners. Fine blades. Grey-green.
• Fescue. Narrow, smooth-edged blades with pointed tips. Medium to dark green.
• Ryegrass. Glossy, narrow, pointed blades. Grows in clumps with fibrous roots. Bright green.
• Kentucky Bluegrass. Narrow, smooth blades with boat-shaped tips. Soft texture. Blue-green. 

Note: In some newer subdivisions, builders and landscapers use different types of grass in the front and rear yards. Make sure you inspect both areas to prevent surprises when mowing.

End Notes

If you hire someone to mow your grass - lawncare professionals, or the neighbor’s kid - make sure that they know your grass species, the recommended grass cutting heights, and the one-third rule. Lawn damage can be expensive to repair.