Vertical mowing, also known as verticutting or vertical cutting, is a specialized lawn care technique that uses vertical blades to cut into the turf layer rather than horizontally across the top of the grass blades. This process works to thin the turf canopy and slice through the layer of organic debris that accumulates between the actively growing grass and the soil surface. This method is distinct from regular mowing, which focuses only on reducing the height of the grass blades for an aesthetic finish.
The Mechanism of Vertical Mowing
A vertical mower is equipped with a reel of thin, rigid blades oriented perpendicular to the soil. These blades rotate rapidly as the machine moves forward, slicing vertically into the turf. The depth of the cut is adjustable, allowing the blades to penetrate the dense layer of organic matter, which can include dead grass, roots, and stems, or even lightly into the soil.
When set correctly, the blades catch laterally growing stems, known as stolons or rhizomes, cutting them to encourage a denser, more upright growth habit. This slicing motion pulls the accumulated organic material, or thatch, up to the surface of the lawn where it can be collected.
Primary Goals of Vertical Mowing
Vertical mowing controls the accumulation of thatch, a tight, spongy layer of living and dead plant matter between the grass blades and the soil. While a thin layer of thatch less than half an inch can be beneficial, excessive buildup acts as a barrier, preventing water, air, and essential nutrients from reaching the root zone. Slicing through this barrier helps restore the flow of these resources.
Vertical cutting is also an effective method for preparing a lawn for overseeding by creating precise grooves in the soil surface. These small channels ensure superior seed-to-soil contact, which is a requirement for successful germination and establishment. Furthermore, this technique manages turf grain, especially in grass types like Bermuda grass, as the vertical blades prune horizontal stems and stimulate new, upright shoot growth.
When and How to Vertically Mow
Timing and Recovery
Timing the vertical mowing process depends on the type of grass and its active growing season to ensure quick recovery. For cool-season grasses, the best times are early fall or early spring, coinciding with optimal recovery conditions. Warm-season grasses, such as Bermuda and Zoysia, should be vertically mowed in late spring or early summer when they are actively growing. Avoid performing this procedure during periods of high heat, drought, or when the grass is under stress, as this can severely damage the turf.
Preparation and Execution
Execution requires careful preparation, beginning with lowering the regular mowing height slightly below its normal level a few days before the procedure. Setting the blade depth is important; for thatch removal, the blades should be set to just penetrate the thatch layer, typically no more than one-quarter to one-half inch into the soil. Aggressive thatch removal may require a cross-hatch pattern, making a second pass perpendicular to the first. Always start with a conservative depth and gradually increase it if necessary, as cutting too deep can damage the grass crowns and roots.
Necessary Steps After Vertical Mowing
Promptly remove the large amount of debris, or thatch, that has been pulled to the surface. This material must be raked or collected with a bagger and removed from the lawn to prevent it from smothering the remaining grass and hindering recovery.
Post-procedure care is essential for recovery. Thorough, deep watering should be performed immediately after cleanup to prevent exposed roots and crowns from dehydrating. If the vertical mowing was done for overseeding, apply the new seed right away, followed by a light application of starter fertilizer. Avoid heavy foot traffic for several days to allow the turf to begin its recovery period.