The start of the grass cutting season marks the transition from winter dormancy to active lawn growth. Determining the precise time to begin mowing is often confusing because it is not tied to a fixed calendar date. Instead, the start of the mowing season is triggered by biological and environmental factors that signal the grass is ready to grow.
The Biological Trigger: Soil Temperature and Grass Types
The single most reliable indicator for when grass cutting season begins is the temperature of the soil, not the air. Air temperature fluctuates daily, but the soil warms more slowly and consistently, triggering the grass plant to emerge from dormancy and begin root development. A soil thermometer inserted a few inches into the ground is the best tool for accurate measurement.
The required soil temperature depends on the type of grass in your lawn. Cool-season grasses (Kentucky bluegrass, fescue, perennial ryegrass) dominate northern climates and begin growing when the soil consistently reaches 50–65°F (10–18°C). Warm-season grasses (Bermuda grass, Zoysia, St. Augustine) found in southern regions require a higher, more sustained soil temperature of 65–70°F (18–21°C) before they actively begin spring growth. Cutting the lawn before these thermal thresholds are met risks stressing the grass while it is still vulnerable.
Pre-Mow Preparations: Getting the Lawn Ready
Before the first cut, a few preparatory steps ensure a healthy season. The first task involves a thorough cleanup of the lawn area. Removing winter debris, such as fallen branches, leaves, and trash, prevents them from smothering the grass and dulling mower blades.
Inspect the lawn for common winter damage, particularly snow mold. This fungus appears as matted patches of grass with white or gray webbing that prevents new blades from growing through. Lightly raking these affected areas helps break up the matted grass and encourages air circulation. Check for soil compaction by pushing a screwdriver into the turf; if insertion is difficult, the soil is likely compacted. Finally, the mower requires attention, as the first cut should always be done with freshly sharpened blades. A sharp blade creates a clean cut, allowing the grass to heal quickly and reducing the risk of disease, while a dull blade tears the grass, leaving ragged, brown tips.
The Essential First Cut: Setting the Right Height
The first cut is a gentle transition from dormancy requiring a specific technique. It must adhere to the “one-third rule,” meaning you should never remove more than one-third of the grass blade height in a single mowing session. If the grass is taller than usual, the first cut should be done at the mower’s highest setting to trim only the tips and remove dead or winter-burned grass.
This initial height should be slightly higher than the height maintained during peak summer months. Cutting the grass too short, or “scalping” it, can shock the plant and deplete the energy reserves needed for spring root development. For the first cut, especially if the grass is long, it is advisable to bag the clippings to prevent thick layers from smothering new growth. Subsequent cuts can usually be mulched, but the heavy volume of the first mow may create clumps that block sunlight and promote disease.
Establishing the Seasonal Mowing Routine
Once the initial cut is complete, the routine is determined by the grass’s growth rate, not a fixed schedule. During early spring, when temperatures are ideal and moisture is abundant, grass growth accelerates rapidly. This rapid growth phase may require mowing as frequently as once a week, or even more often for fast-growing species like Bermuda grass or Kentucky bluegrass.
The frequency of mowing must always be dictated by the one-third rule to ensure the lawn’s health. If the grass reaches a height where removing only one-third of the blade requires mowing every three to four days, the routine must be adjusted. As the season progresses into summer, growth naturally slows down, particularly for cool-season grasses, and the mowing frequency can decrease to bi-weekly or as needed. The goal is to maintain a consistent height without shocking the plant by removing too much leaf tissue at once.