Sod refers to pre-grown sections of grass, including the soil and root system, typically delivered in rolled-up strips of turf. Laying new sod is a common way to establish a lawn quickly, but the first few weeks following installation represent a delicate period for the grass. During this initial phase, the turf must transition from being grown elsewhere to establishing a new, permanent root system in your native soil. Mowing the new lawn before this root establishment is complete is often the single biggest error new sod owners make, as it places undue stress on the fragile grass.
Determining the Ideal Time for the First Mow
The primary goal after laying new turf is to encourage the roots to knit securely into the underlying soil. Generally, this establishment period requires a minimum waiting time of ten to fourteen days. This timeline can shift depending on external conditions, such as the season, weather patterns, and the specific species of grass used.
Before any cutting begins, a physical assessment is necessary to confirm the sod is securely anchored. This is commonly known as the “lift test,” which indicates root development. To perform this test, gently grasp a corner or edge of a recently laid piece of sod and slightly pull upward without applying excessive force.
If the sod resists the gentle pulling and remains firmly anchored, the new roots have successfully grown into the soil below. If the piece lifts easily or tears away, root knitting is incomplete, and more time is required. Even if the grass blades grow tall, only the successful completion of the lift test should serve as the definitive green light for the first cut.
Proper Technique for the Initial Cut
Once the lift test confirms root establishment, specific methods must be employed for the initial cut. Ensure the mower blade is sharp, as a clean cut promotes quick healing. A dull blade tears the grass, leaving ragged ends that can invite disease and cause stress.
The principle of the “one-third rule” should be strictly followed during this first mowing session. This rule dictates that you should never remove more than the top one-third of the grass blade height in a single cut. For example, if the grass is six inches tall, the mower should be set to remove only two inches.
Set the mower deck to the highest setting, often 3.5 to 4 inches, to minimize stress on the young root system. Maintaining a higher cutting height encourages deeper root growth and provides necessary shading for the root zone. Always ensure the soil surface is dry enough to support the weight of the mower without creating ruts.
During this first cut, bag the clippings instead of leaving them on the lawn surface. Removing the clippings prevents them from clumping together and smothering the tender grass blades beneath.
Consequences of Premature Mowing
Mowing new sod before the root system has adequately knitted into the subsoil can lead to several negative outcomes. One immediate risk is the physical displacement or tearing of the sod pieces, as the force and vibration of the mower can pull up poorly anchored sections, creating gaps.
When the protective covering of the grass blades is removed too soon, the turf becomes highly susceptible to desiccation, or drying out. Tearing or lifting the pieces disrupts the fragile connection between the sod and the moist soil, causing the edges to shrink and the entire piece to lose water rapidly.
This stress diverts the plant’s limited energy resources away from the primary task of root establishment. This recovery process significantly delays the overall root knitting timeline, leaving the sod vulnerable for an extended period.