Sod provides an instant lawn, but it is not instantly established. While the grass blades are mature, the root system is initially fragile and disconnected from the underlying soil. The first mowing is sensitive because premature or incorrect cutting stresses the young grass, hindering root development and delaying establishment. Successfully navigating this first cut is a determining factor for the long-term health and uniformity of the new lawn.
Determining the Ideal Time for the First Cut
The timing of the initial mow depends on the physical readiness of the sod, not a fixed calendar date. Before mowing, the grass blades should reach a height of at least 3.5 to 4 inches to ensure they can withstand the stress of cutting.
The most reliable way to confirm readiness is to perform a gentle test on the sod. This “tug test” involves lightly pulling up on a corner or seam of the sod piece. If the sod lifts easily, the fine, white roots have not yet penetrated and anchored into the soil beneath, and the sod is not yet ready to be mowed. If the sod resists the gentle pulling and remains firmly secured to the ground, it indicates that root establishment has progressed sufficiently to support the weight of a mower and the act of cutting. It is beneficial to temporarily reduce watering the day before the planned mow to allow the soil to firm up, preventing the mower’s weight from creating ruts or causing soil compaction, which is detrimental to new root growth.
The Technique of the Initial Mowing
Using a walk-behind push mower is preferable over a heavier riding mower, as the reduced weight minimizes the risk of damaging the soft, newly rooted turf. Ensure the mower blades are razor sharp to achieve a clean cut. Dull blades tear the young grass, leaving ragged edges that increase the plant’s stress and vulnerability to disease.
Set the mower deck to its highest possible setting, strictly adhering to the “one-third rule.” This rule dictates that you should never remove more than one-third of the grass blade’s total height in a single session, as cutting more can shock the grass and set back root establishment. The grass must be completely dry when mowed; wet clippings clump, smothering the new turf, and moisture makes the blades susceptible to tearing. Bag the clippings from the initial cut to prevent heavy debris from settling on and damaging the fragile new grass.
Establishing a Routine After the First Mow
Once the sod has successfully tolerated the first cut, the focus shifts to establishing a regular mowing schedule that promotes continued root growth. During the initial establishment phase, which can last several weeks, the frequency of mowing often increases to every five to seven days. This schedule ensures that the grass does not grow excessively tall between cuts, allowing the one-third rule to be maintained without stressing the plant.
Gradually reducing the overall cutting height is necessary. After the first few cuts at the highest setting, the mower deck should be lowered slightly with each subsequent mow until the lawn reaches the desired maintenance height for the specific grass type. It is important to maintain a proper watering regimen throughout this period to support the new routine, ensuring that the grass receives the moisture needed for deep root development.