Question:
Is it true that I can mow less often if I cut the grass really short?Answer:
The frequency of mowing should be based on the growth of the grass. As a general rule, mow as often as needed so that no more than one-third of the total leaf area is removed in a single mowing. Removing more than one-third is detrimental because it reduces the reserve carbohydrates within the plants that are used to regrow shoots and leaf tissue after mowing. Depleting the carbohydrates reduces the capability of the grass plant to withstand environmental stresses. Making the lawn more prone to drought damage, disease issues, and weed pressures.
Contrary to popular belief, shorter mowing heights require more frequent mowing, not less. A lawn maintained at a short 1-inch height would have to be mowed when the grass reaches just 1.5 inches tall (after a half inch of growth) to not remove more than one-third of the total leaf area. However, a lawn maintained at a 3-inch height would have to be mowed when it reaches 4.5 inches tall to not remove more than one-third of the total leaf area (after the grass grows 1.5 inches).
This means that if the daily growth rate is 0.2 inches per day, it would take just 2.5 days for the turf to grow one-half an inch, but 7.5 days for it to grow 1.5 inches. So at a 1-inch height, you would mow every 2.5 days to not remove more than a third of the leaf material, but at a 3-inch height, you would mow every 7.5 days.
In the table below, you can compare how the height of the grass influences the mowing frequency when you adhere to the one-third guideline.
| Mowing Height | Height of Grass at Mowing | Amout of Grass Removed | Estimated Mowing Frequency* |
|---|---|---|---|
| 0.5 in | 0.75 in | 0.25 in | 1.3 days |
| 1.0 in | 1.5 in | 0.5 in | 2.5 days |
| 1.5 in | 2.25 in | 0.75 in | 3.8 days |
| 2.0 in | 3.0 in | 1.0 in | 5.0 days |
| 2.5 in | 3.75 in | 1.25 in | 6.3 days |
| 3.0 in | 4.5 in | 1.5 in | 7.5 days |
| 3.5 in | 5.25 in | 1.75 in | 8.8 days |
| 4.0 in | 6.0 in | 2.0 in | 10.0 days |
* Estimate based on a daily growth rate of 0.2 inches.