Here's What'll Happen If You Install Lawn Mower Blades Upside Down

Mowing is one of the most common yard maintenance tasks homeowners perform each week to keep their lawns healthy and attractive. A well-maintained lawn mower is crucial if you want a luscious green yard. One important maintenance task is keeping your mower blades sharp. When reinstalling the blade after sharpening, make sure it's facing the correct direction. If your lawn mower blades are installed upside down, you'll be cutting the grass with the dull side of the blade. This can result in badly cut grass that is damaged, uneven, frayed at the ends, and choppy-looking.  

If you keep mowing with the blade installed upside down, the grass will never look neatly trimmed, no matter how often you mow. Over time, the grass may stop growing, and bald patches could develop on your lawn. In addition to harming your grass, the mower itself could also get damaged. Because of the blade's design, the wings — which should face the lower deck — will constantly hit rocks, grass, soil, and debris, leading to damage. The wings can develop cracks, or the blade can become bent, requiring replacement. In severe cases, it's also possible for the crankshaft to break.

The best way to avoid damaging your grass — or your mower — is to make sure that the mower blades are installed properly. Before replacing or installing mower blades, disconnect the spark plug on gas models and remove the battery or unplug electric ones. You also want to empty the gas tank before tipping a gas-powered mower to prevent spills or leaks. Take a picture of the blade that is on the mower before you remove it, so you can use it as a reference when reinstalling. This will help ensure you are putting the mower blade on the right way. If you're just trying to refresh your mower, there is a way to sharpen the blades without removing them, saving you the hassle of reinstallation.

Carefully remove the old blade and set it aside. Some new blades are labeled with phrases like 'grass side' or 'this side down'. If your new blade includes printed instructions, follow them to install it correctly. If there are no markings, check for a beveled edge. Both the beveled edge of the blade and the wings should face up toward the mower deck. Once the blade is on correctly and facing the right direction, insert the bolt and tighten it by hand to make sure it is threaded properly. Then, use the socket wrench to finish tightening it, ensuring that you don't over-tighten the bolt and strip it. Carefully set the mower back onto its wheels, reconnect the spark plug, and perform a test run to make sure it's all working properly.