Of all the mistakes people make when caring for their lawns, cutting the grass too short might be the most harmful. “Grass blades are like solar panels, absorbing energy from the sun and sending it down to the roots,” explains Frank Rossi, associate professor of horticulture at Cornell University’s School of Integrative Plant Science. “When you cut off all that foliage, the grass is forced to live off its energy reserves, and a stressed-out lawn is not going to look very good.”
Besides being more disease-resistant, taller grass does a better job of blocking out weeds, meaning fewer dandelions to deal with; and it provides thicker shade cover for the soil, reducing evaporation and helping the lawn through dry spells.
To avoid scalping your grass, Rossi recommends following the 1/3rd rule, whereby you never take off more than 1/3rd of the height of the grass. That’s probably longer than you’re used to, but besides reducing plant stress and water-loss, it means you won’t have to mow as often, “about 25% to 35% less frequently,” says Rossi.
Here’s what the math looks like on that claim:
For best results, lawn care experts recommend letting the grass grow to a little more than 5 inches, then cutting it back to around 3.5 inches, removing about 1/3rd of the blade.
Compare that with someone who cuts their lawn down to 2 inches, going for a more manicured look. To do that and still follow the 1/3rd rule, they will need to cut the lawn when it reaches 3 inches. That’s 1 inch of growth between cuttings versus 1.5 to 2 inches under the best-practices scenario. Which translates into mowing every 5 days instead of every 8 or 9 days. Multiple that out over the course of the entire growing season, and you get back a few extra Saturdays!
Rossi is a big fan of robotic lawn mowers, which he estimates are now used on about a third of the lawns in Europe, though they’re just starting to gain popularity in the U.S. Robotic mowers only trim a little of the lawn at a time using small, razor-like blades. That more frequent mowing keeps the lawn healthy and also providers natural fertilizer in the form of nutrient-rich fine clippings.
How to Set Your Mower Height
Most of the lawn mowers tested by our experts in the Home Improvement & Outdoor Lab at the Good Housekeeping Institute have an adjustable deck, usually with a notched lever that raises or lowers the wheels in 1-inch or 1/2-inch increments, adjusting the distance between the deck and the ground. It’s a good idea to measure the height of the mower blade from the ground (use the driveway or other level surface to get an accurate reading). You might find that the notches are a bit off, maybe in such a way that the 4-inch setting is best for cutting your lawn to the desired 3.5-inch height.
More Lawn Care Mistakes to Avoid
For a lush, healthy lawn, avoid these other common lawn care mistakes:
✔️ Mowing with a dull blade. It will tear at the grass blades, leaving behind jagged edges that loose water and invite disease. Experts recommend sharpening your blade every 10 hours of mowing. It’s a good idea to have a second blade that you can use while the first is at the hardware store or lawn mower repair shop.
✔️ Bagging, instead of mulching. Lawn clippings are a natural source of nutrients for the lawn that can reduce fertilizing needs by 25% or more. So instead of bagging them (which adds time and effort to the chore), use your mower’s mulching mode to deposit the clippings back onto the lawn.
✔️ Pulling every last weed. Forget about the perfect, weed-free yard. It’s tough to achieve without pumping the lawn full of chemicals. Plus, some weeds are actually good for turf grass. Clover, for examples, pulls nitrogen from the air and feeds it to the soil.
✔️ Watering every day. A daily sip won’t help your lawn’s root system. A good long soak once a week (or every few days during high summer) is a better irrigation strategy. Lawn’s need about 1 inch of water per week, including rainfall. An empty tuna can is a good way to keep track.
Having written thousands of product reviews and how-to articles on all aspects of home ownership, from routine maintenance to major renovations, Dan (he/him) brings more than 20 years of industry experience to his role as the director of the Home Improvement & Outdoor Lab at the Good Housekeeping Institute. A one-time roofer and a serial remodeler, Dan can often be found keeping house at his restored Brooklyn brownstone, where he lives with his wife and kids.
