The first mow of the season signals the true end of winter dormancy for a lawn. The timing of this initial cut is not determined by a fixed date on a calendar but by a combination of environmental and physical factors unique to each location. Understanding these indicators is the foundation for establishing a healthy, resilient turf for the entire growing season. Starting too early can shock the grass, while waiting too long creates a difficult and stressful cut. The goal is to catch the grass at the exact point it begins active growth.
Reading the Indicators: When is Grass Ready to Be Cut?
The most reliable indicator that your lawn is ready for its first trim is the temperature of the soil, not the air. This ground warmth signals the grass plant’s root system to emerge from winter dormancy and begin actively drawing nutrients and moisture. Turfgrasses are broadly categorized as either cool-season or warm-season, and each type has a specific temperature threshold for growth.
Cool-season grasses, like Kentucky Bluegrass and Fescue, begin to wake up when the soil temperature consistently reaches 55 degrees Fahrenheit at a depth of a few inches. Their period of peak growth occurs when temperatures stabilize between 60 and 75 degrees Fahrenheit. Warm-season grasses, such as Bermuda and Zoysia, require the soil to be warmer, typically needing a consistent 65 degrees Fahrenheit to initiate strong, active growth.
Beyond soil temperature, the physical height of the grass blades is the most visible sign that mowing is necessary. For most cool-season varieties, the grass should reach a height of approximately three to four inches before the first cut. Warm-season grasses generally need to reach a similar height before their initial trim. This minimum height ensures the plant has developed enough leaf surface area to support the root structure that grew during the early spring.
The final check is the state of the lawn itself. The soil should be firm and dry to the touch, not soggy from melting snow or spring rain. Mowing wet or saturated turf can compact the soil beneath the blades, which restricts the flow of oxygen and water to the roots, causing long-term damage. Waiting for the lawn to dry prevents the mower wheels from tearing up the grass and leaving ruts.
Regional Guidelines for the Initial Mow
While local conditions are the ultimate factor, general regional timelines offer a helpful starting point for planning the first cut. These calendar estimates correlate with the average dates that soil temperatures reach the necessary thresholds for active growth in different climate zones.
In the Deep South and Southwest, where warm-season grasses like St. Augustine and Bermuda exist, the first cut can be expected as early as late February or throughout March. These areas experience the fastest ground warming, quickly pushing soil temperatures past the 65-degree mark. In frost-free coastal areas, some mowing may even occur year-round, though a true first seasonal cut happens as growth accelerates.
The Transition Zone, which covers the mid-Atlantic and mid-southern states, has a more variable start date, often falling in mid-April. This is where both cool-season and warm-season grasses can be found. Cool-season grasses here will initiate growth earlier in the season than the warm-season varieties, meaning the first mow for different lawns in the same neighborhood can vary by several weeks.
For the Northern, Midwest, and New England regions, where cool-season grasses dominate, the first cut is typically delayed until late April or early May. The ground in these areas retains winter cold for a longer period, delaying the soil’s consistent warm-up to 55 degrees Fahrenheit. In areas that experience heavy snow cover, the start date is pushed back.
The First Cut: Height, Prep, and Technique
Once the environmental indicators confirm the grass is ready, the inaugural mow requires a specific technique to ensure the plant’s health. Before the blades make contact with the first patch of new growth, sharpening them is recommended.
Dull mower blades tear and shred the grass tips instead of cleanly slicing them, leaving behind ragged ends that turn brown and stress the plant. This damage makes the grass susceptible to disease. Clearing the lawn of any winter debris, such as fallen branches and stones, is necessary to protect the freshly sharpened blade from becoming nicked or bent.
For the actual cut, the most important rule to follow is the “one-third rule,” which dictates that you should never remove more than one-third of the grass blade’s total height in a single mowing session. For example, if the grass is four and a half inches tall, the mower should remove no more than one and a half inches. Violating this rule removes too much photosynthetic surface, forcing the plant to draw on stored energy and weakening the root system.
For this initial cut, set the mower to one of its highest settings, especially for cool-season grasses, to ensure you comply with the one-third rule. Bagging is often advisable for the first mow, even if you normally mulch. Bagging removes the large volume of dormant, brown material and any accumulated winter debris.