The arrival of spring signals the end of winter dormancy and the beginning of active growth for your lawn. The first few cuts of the season establish the growth patterns and resilience of the turf for the entire year. Approaching this initial mowing strategically sets the stage for a healthy, dense lawn. This requires understanding when to start mowing and how much of the grass blade to remove.
Determining When to Start Mowing
The calendar date is less important than the conditions on the ground when deciding on the first mow of the year. Grass should be actively growing, which is primarily dictated by soil temperature, not just the air temperature. Cool-season grasses, such as Kentucky bluegrass and fescue, begin significant growth when the soil consistently reaches 45 to 55 degrees Fahrenheit.
Warm-season grasses, like Bermuda or Zoysia, require a higher soil temperature, waiting until the ground is consistently around 60 to 65 degrees Fahrenheit before exiting dormancy. Attempting to mow before the grass is fully awake can stress the plant and hinder its recovery from winter. You must also consider the moisture content of the soil. Wait until the ground is dry enough to walk across without leaving deep footprints or feeling squishy underfoot, as mowing saturated soil leads to compaction, creating ruts, and damaging the root structure.
Applying the One-Third Rule for Spring Height
Cutting grass short in spring is not recommended. Aggressively cutting the grass very short, known as scalping, stresses the entire plant. Scalping forces the grass to use up stored energy reserves intended for future growth. This practice also exposes the fragile crown, which is the growing point, making it vulnerable to heat, pests, and disease.
Instead of cutting short, adhere to the “one-third rule” for healthy turf management. This rule states that you should never remove more than one-third of the grass blade’s total height in a single mowing session. For instance, if your desired cutting height is three inches, mow when the grass reaches a maximum of four and a half inches tall. This ensures enough leaf tissue remains for efficient photosynthesis, which creates the energy needed for growth.
If the grass has grown excessively tall over the winter, do not attempt to bring it down to the desired height in one pass. Gradually reduce the height over several consecutive mowing sessions, maintaining the one-third rule each time. For example, if the grass is six inches high and your goal is three inches, the first cut should be no lower than four inches. This gradual approach minimizes shock and allows the grass to adapt to the new height without compromising its health.
Promoting Turf Health Through Early Season Mowing
Following the one-third rule, particularly in the spring, benefits the lawn’s long-term health. When the proper amount of leaf tissue is removed, the plant shifts its energy toward lateral growth. This leads to a denser turf canopy that naturally crowds out weeds and fills in thin areas left over from winter.
A slightly taller grass height, maintained by correct spring mowing, shades the soil surface. This shading effect suppresses the germination of weed seeds, which require sunlight to sprout. Leaving the grass blades at a healthy height encourages the plant to develop a deeper, more robust root system. Stronger roots allow the grass to become more resilient, more water-efficient, and better prepared to withstand the stresses of summer heat and drought.