Don't Bother Fertilizing Your Lawn Twice a Year

Fertilizing your yard too often—or at the wrong time—can do more harm than good

By Mary H.J. Farrell

A lush lawn can make your home’s landscaping shine (and make your neighbors green with envy). But how do you maintain a beautiful and healthy yard year-round?

The answer is fertilizer.

Fertilizing provides the nitrogen that grass needs to better withstand pests and extreme heat and cold. But how frequently you fertilize your lawn can make the difference between a well-kept yard and one that looks worse for wear.

Overfertilizing can damage roots and cause scorching, leaving grass brown and patchy. Underfertilizing, though, can make grass less pest- and disease-resistant. And rules of thumb—such as fertilizing twice a year—don’t apply to every lawn, since weather conditions and grass cycles can vary depending on where you live.

The right time to apply fertilizer is when the grass is growing more roots than blades. In the Northeast and Northwest, that’s usually in the fall. In the South and Southwest, it’s in the late spring. So in cooler climes, don’t even think about it until Labor Day. And if you only fertilize once a year, do it in September using fall fertilizer. (Most high-quality fertilizers contain slow-release nitrogen, which promotes growth in the spring.)

How often you mow is also a factor in whether you have a lush lawn. Generally, you should let grass grow to 4½ inches and then cut it to 3 or 3½. Tall grass helps promote deep roots, making your lawn hardier and more resilient.

Another way to add nutrients is to use the mulch setting on your mower and leave the clippings behind. This also reduces evaporation.

And don’t overwater your lawn. A typical lawn needs no more than 1 inch of water a week, including rainfall. To promote deep roots, give your lawn one long soak each week instead of several short waterings. In fact, a light daily watering encourages root systems that are too shallow, promotes weed growth, and leaves grass susceptible to disease and insect damage.

Bottom line: Listen to your lawn and apply fertilizer only when the grass calls for it.

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