Lawn maintenance involves two distinct cutting processes: mowing and trimming. Mowing uses a rotary mechanism to uniformly cut large, open areas of turfgrass, setting the overall height of the lawn. Trimming, also known as weed whacking or string trimming, uses a monofilament line to cut grass in confined spaces, along obstacles, and for creating a crisp edge. The established practice is to always perform large-area mowing before engaging in detailed perimeter trimming. This order optimizes the workflow and contributes to a cleaner, more professional result.
The Recommended Order: Mowing Before Trimming
The sequence of mowing followed by trimming is the standard among lawn care professionals for logistical efficiency. The initial pass with the lawnmower addresses the bulk of the yard, often encompassing 90% or more of the total turf area, reducing the entire lawn to the desired, uniform height. This large-scale operation sets the baseline for the entire project.
Once the main area is cut, the focus shifts to using the string trimmer, a high-precision tool. The trimmer addresses perimeter areas that the wider mower deck cannot access, such as grass around trees, mailboxes, and fences. This structured, two-part approach ensures the highest level of uniformity and prevents the need to re-cut already trimmed sections.
The Efficiency Rationale: Utilizing the Mower for Cleanup
The most compelling reason for trimming after mowing relates directly to debris management. String trimmers operate at high RPMs, atomizing grass blades into smaller, lighter particles than those produced by the mower’s shear cut. These lightweight clippings are easily dispersed onto hard surfaces like sidewalks, patios, and driveways, or deposited along flowerbed borders. These scattered clippings create a messy perimeter that would otherwise require manual cleanup.
By performing the trimming operation immediately after the mower has passed, the subsequent step of lawn care can efficiently manage this debris. The high-speed rotation of a mower blade creates a powerful updraft, known as the vacuum action, which is designed to lift and collect cut grass. The air flow generated by the blade is highly effective at gathering the light, scattered trimmer debris.
A final pass with the mower can be directed over the areas where the trimmer clippings have settled. This allows the mower’s vacuum action to collect and process the scattered debris from the trimming operation, effectively cleaning the hard surfaces without requiring a separate tool. This simple change in sequence eliminates the time and effort needed for an additional cleanup step.
Setting the Right Height for a Clean Finish
Another significant benefit of the mow-first sequence is achieving a visually seamless transition between the main lawn and the perimeter edges. The trimmer’s function is to perfectly match the height established by the lawnmower deck. If trimming occurs first, it becomes challenging to accurately gauge the exact finished height, often leading to uneven or visibly choppy edges once the mower completes its work.
When trimming after mowing, the operator can hold the weed whacker so the cutting plane of the monofilament line aligns precisely with the height of the recently cut turf. This technique ensures that the grass along the edges is cut to the identical length as the rest of the lawn. Maintaining this height alignment prevents the common issue of scalping—cutting the grass too short—and creates a professional, uniform appearance.