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Setting and sharpening your mower blade correctly ensures the blade cuts the grass at the right height, making it more resistant to disease, while retaining moisture in the soil and controlling weeds, reducing excessive watering, and eliminating the need for synthetic fungicides and herbicides.

How to set and sharpen your mower blade correctly

When to sharpen your mower blade

If you have a gasoline mower, it should be serviced every year to keep it in good running shape and reduce its air polluting emissions. The repair shop will sharpen the blade as part of a yearly tune-up. After that, the blade will need a tune-up after every eight to 12 hours of mowing time.[1] Look closely at your grass after mowing: if the tips of the grass look shredded rather than cleanly cut, it's time to sharpen your mower blade.

If you have an electric or push mower (or you do your own tune-up) you will need to learn how to take blade off the mower so you can take it to be sharpened or sharpen it yourself. Local hardware stores, lawn and garden equipment repair services, or sharpening services will sharpen mower blades.

Removing a rotary mower blade

Tools you need to remove the blade from a rotary mower:

• clamp
• 2-by-4
• socket wrench
• penetrating oil (such as WD-40)

For illustrated instructions on how to remove your rotary mower blade see The Family Handyman - Sharpening Mower Blades, Axes, and Shovels. As a safety precaution, always remove the spark plug first if you have a gasoline mower. Although unlikely, the mower could start accidentally.

Sharpening a rotary mower blade

Tools you need to sharpen the blade:

• 10-inch bastard mill file
• bench vise
• blade balancing tool (or you can use a horizontally-hung nail)
• rotary bench grinder (only needed for large nicks, costs about $50)

A rotary bench grinder is only needed for a badly-nicked blade. If you are not an avid do-it-yourselfer, you may want to take a blade that needs grinding to a professional.

For step-by-step illustrated instructions on how to sharpen your rotary mower blade see The Family Handyman - Sharpening Mower Blades, Axes, and Shovels.

Sharpening and adjusting your reel mower blades

With a reel mower, you need to both sharpen and adjust the blades. Adjusting the blades is different from setting the blades' cutting height. The blade adjustment adjusts how the reel turns inside the mower, keeping the blades cutting properly when the reel turns. Before you sharpen your reel mower blades, be sure they actually need it: 95 percent of all issues can be solved by making sure the blades are properly adjusted.[2] For instructions on how to adjust the blades on a Scotts Classic, American Lawnmower, or Great States reel mower, see ReelMower - Adjusting the blades on a Scotts Classic mower.

For step-by-step instructions on how to sharpen reel mower blades see ReelMower - Getting started with sharpening a reel mower.

Setting mower blade height

Setting the mower blade height changes the height at which your grass is cut. The proper height for the blade is determined by:

• type of grass
• season and weather conditions
• current height of the grass

Different types of grasses require different cutting heights. Grasses with a coarse leaf texture and lower density may require a higher mowing height for a better-looking lawn with fewer weeds.[3] Below are the appropriate grass cutting heights by type of grass:[4]

• Kentucky Bluegrass: mow at 1 1/2" to 2 1/2"
• Rye grass: mow at 1 1/2" to 2 1/2"
• Fescue: mow at 1 1/2" to 2 1/2"
• Tall Fescue: mow at 1 1/2" to 3"
• Bermuda: mow at 1/2" to 1"
• St. Augustine: mow at 1" to 3"
• Bentgrass: mow at 1/4" to 3/4"
• Centipede grass: mow at 1" to 2"
• Zoysia: mow at 1/2" to 1"
• Buffalo grass: mow at 2 to 3 inches, or leave it completely unmowed

Cutting height should also vary by season. When grass is growing quickly in the spring, the cutting blade can be set lower. In the hottest part of summer when growth is slow, set the blade higher. In times of little rain, either don't mow, or keep the blade really high: tall grass is better protected from drought. Before the onset of winter in colder climates, mow to about 2 inches high.[1]

If the grass is long overdue for cutting, don't cut it all at once. Never cut more than one-third it's length on any one day.[1]

Find it! To sharpen and set mower blades

Useful products for sharpening your mower blade include:

Setting and sharpening your mower blade correctly helps you go green because…

• A sharp blade keeps grass healthy and disease-resistant, eliminating the need for harmful synthetic pesticides.
• Setting your mower blade at the right height discourages weed growth, eliminating the need for harmful synthetic herbicides.
• Setting your mower blade at the right height saves water: cut too short, grass must be watered to make up for the loss of leaf surface, and the extra watering can lead to crab grass and fungal disease, which then require herbicides and fungicides.[5]
• Setting your mower blade at a higher setting, and mowing less often, reduces air pollution, noise pollution, and volatile organic compounds (VOCs) caused by gasoline-powered lawn mowers.

There are about 31.6 million acres of turf—almost 50,000 square miles—in the US. Lawns (including residential and commercial lawns, as well as golf courses) could be considered the single largest irrigated crop in America in terms of surface area, occupying three times more land than is devoted to irrigated corn. About 200 gallons of fresh water per person per day would be required to provide adequate water for the nation’s lawn surface area.[6]

A lawnmower used for one hour creates as much air pollution as a car driven for 20 miles. Each year in the US, $5.2 billion is spent on fossil fuel-based lawn fertilizers; 67,000,000 pounds of synthetic lawn pesticides are applied; and 580 million gallons of gasoline are used in lawnmowers. Depending on the city, 30 to 60 percent of fresh water in urban areas is used to water lawns.[7]

Setting your mower blade at the highest recommended setting retains moisture in the lawn and prevents unnecessary watering and mowing, saving water and reducing air pollution. Keeping a sharp mower blade makes for a healthier lawn and eliminates the use of harmful herbicides and fungicides.

Related health issues

The chemical 2,4-D (2,4-dichlorophenoxyacetic acid) is one of the most commonly used herbicides in the US and is used in lawn care products to kill broad-leaf weeds like dandelions. Approximately 12 to 28 million pounds of 2,4-D is used each year in non-agricultural settings. Combining 2,4-D with a related chemical called 2,4,5-T created the cancer-causing defoliant Agent Orange, used during the Vietnam War. Although 2,4,5-T was banned by the US Environmental Protection Agency (EPA), use of 2,4-D is still permitted, although its health effects are under review.[8]

A study conducted by the American Veterinary Medical Association found that certain breeds of dogs are four to seven times more likely to contract bladder cancer when exposed to chemically treated lawns.[1]

Glossary

• fungus: An organism which produces spores and cannot manufacture chlorophyll, including molds, mildews, rusts, smuts, mushrooms, and yeast.
• fungicide: An agent that kills fungi.
• herbicide: An agent used to destroy or inhibit plant growth.
• reel mower: Mower in which the blades are on a revolving cylinder.
• rotary mower: Mower in which the blade is flat and spins horizontally.

External links

• The Family Handyman - Sharpening Mower Blades, Axes, and Shovels Follow step-by-step illustrated instructions and learn how to sharpen your rotary mower blade, as well as other home and garden tools.
• ReelMowers - Getting started with sharpening a reel mower Follow step-by-step illustrated instructions and learn how to sharpen your reel mower blades.
• ReelMowers - Changing the cutting height for the Scott's Classic Mower Learn how to change the cutting height on a Scott's Classic reel mower (applicable to other brands as well).
• ReelMowers - Adjusting the cutting blades for the Scott's Classic Mower Learn how to adjust the cutting blades on a Scott's Classic reel mower (applicable to other brands as well).
• California Integrated Waste Management Board - Mowing Heights for Common California Turf Grasses Learn the proper blade height setting for common California grasses, as well as how long the grass should be before it's time to mow it.
• Mow Like a Pro! The Florida 4-H organization developed this curriculum aimed at educating teens about the basics of operating an entrepreneurial lawn care business. Learn about proper lawn care, and set up your teen for his or her own summer job while you're at it!