The lawn care season marks the period when active growth and necessary maintenance begin, signaling the end of winter dormancy for grasses and the start of biological activity in the soil. The exact start date is highly variable, depending far more on local environmental conditions than on a fixed calendar month. Timing differs across regions and can shift significantly from year to year based on weather patterns.
Using Soil Temperature as the True Indicator
The most reliable way to determine the start of the lawn care season is by measuring the soil temperature, not the air. Soil temperature dictates when weed seeds germinate and when grass roots become metabolically active, making it a much more accurate metric than waiting for a calendar date.
The temperature range of 50–55°F is the significant threshold for spring lawn activity. When soil temperatures consistently reach this range for several days, it signals the start of germination for common summer annual weeds like crabgrass. Applying a pre-emergent herbicide just before the soil hits this temperature is essential to create a protective barrier.
For cool-season grasses, the 50–55°F range also marks the beginning of vigorous root growth and optimal emergence from winter dormancy. You can measure the soil temperature easily by inserting a soil thermometer 2 to 3 inches into the ground.
Check the soil temperature around 8:00 a.m., when the soil is at its coolest point, for the most consistent data. Monitor this temperature for several consecutive days to confirm the trend before making any applications. Applying products too early risks them breaking down before weeds germinate, wasting the application’s effectiveness.
Seasonal Start Windows by Region
Homeowners who do not measure soil temperature can estimate the season’s start based on the climate zone and grass type. These calendar windows offer a broad estimation, but the actual start is always determined by local weather conditions. The U.S. is generally divided into Northern (cool-season) and Southern (warm-season) climates.
The Northern Tier primarily uses cool-season grasses like Kentucky bluegrass and fescue, with the season beginning in early to mid-spring. Initial maintenance, such as debris clearing and equipment preparation, can start as early as March in milder areas, with active growth beginning in April. For the furthest northern regions, the start may be delayed until May due to persistent snow cover and cold temperatures.
Cool-season grasses begin their fastest growth once air temperatures range between 60°F and 75°F, which generally aligns with the March to May window. The first mowing in the transition zone might happen in April, while those further north wait until May. The first pre-emergent application in these regions usually occurs in April.
The Southern Tier, home to warm-season grasses such as Bermuda, Zoysia, and St. Augustine, has an earlier start to the season. Lawns in the Deep South may show signs of green-up and require attention as early as late February or March because the soil warms up sooner in these climates.
Warm-season grasses break their winter dormancy and resume active growth when consistent air temperatures are in the 60s and soil temperatures reach approximately 65°F. This places the main kickoff of the growing season in the April to May range for most Southern and Transition Zone areas. Initial feeding and the first mow occur when the grass visibly begins to green up and grow.
Essential Tasks for Kickstarting the Season
Once soil and air temperatures signal the season’s official start, there are a few immediate actions that set the stage for a healthy lawn. The first task is a thorough debris clearing of the lawn surface. Removing fallen branches, leaves, and other winter debris allows sunlight and air to reach the grass blades, which helps prevent disease.
Next, focus on equipment preparation, including sharpening the mower blades. A dull blade tears the grass, leaving ragged edges that make the lawn more susceptible to disease and stress. Sharp blades ensure a clean cut, promoting healthier new growth from the first mow.
Applying a pre-emergent herbicide is a high-priority task, timed precisely with the soil temperature reaching 50–55°F. This application forms a barrier in the soil that prevents summer weeds, like crabgrass, from sprouting. Proper timing is the most effective way to control these annual weeds before they become visible problems.