Most homeowners mow their grass once a week when they can fit it into their schedule. This usually means after work or on the weekend for the busy people out there. However, grass does not always grow to where it should be ideally mowed once a week. So, the question remains, how often should you cut your grass?
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The One-Third Rule
The rule of thumb is to only cut up to 1/3 of the grass leaf blade per mowing session. For example, let’s assume that you cut your Kentucky bluegrass to 3 inches. To only cut off 1/3 of the grass blade, you would have to cut your grass when it reaches a height of about 4.5 inches. The below table provides a mowing guide to help you meet the 1/3 rule.
| Ideal Grass Mowing Height | Mow Lawn when grass reaches this height |
|---|---|
| 1 Inch | 1.5 Inches |
| 2 Inches | 3 Inches |
| 2.5 Inches | 3.75 Inches |
| 3 Inches | 4.5 Inches |
| 3.5 Inches | 5.25 Inches |
| 4 Inches | 6 inches |
You now probably see why routinely mowing once a week is not always ideal for your lawn’s health. For example, the spring and fall offer prime grass growing conditions in many areas of the United States. Rapidly growing grass during this time of year may be better off being cut twice a week to meet the 1/3 rule. In contrast, a lawn in drought conditions with minimal irrigation would be better off not being mowed until the grass began to grow to meet the 1/3 rule. This could be well beyond one week.
Mowing Heights of Grass Types
There are several types of common grasses that each have an ideal mowing height. If you can identify the type of grass you have in your yard, review the below table to see the best mowing height for your grass type.
| Grass Type | Ideal Mowing Height |
|---|---|
| Kentucky Bluegrass | 2 to 2.5 inches |
| Tall Fescue | 2 to 3 inches |
| Perennial Rye | 1.5 to 2.5 inches |
| St. Augustine | 2 to 4 inches |
| St. Augustine | 2 to 4 inches |
| Centipede | 1.5 to 2 inches |
| Zoysia | 1 to 1.5 inches |
| Bermudagrass | 1 to 1.5 inches |
Determining your Mower Height
To identify the height you are mowing at, you may need to physically measure from the ground to the blade of your mower. Adjust your mower deck height accordingly based on this measurement. Your lawn mower owner’s manual may also indicate the heights of each of your mower deck settings. Below is an excellent video showing how to measure your cutting height.