March represents the transition month for cool-season grasses, shifting from winter dormancy to active growth. Proactive steps taken during this early spring period establish the foundation for a healthy, robust lawn that can withstand summer stresses. Timing is important in March, as rising soil and air temperatures initiate the biological processes governing weed germination and turf revitalization. A successful strategy focuses on awakening the turf, controlling future weed populations, and ensuring the grass has resources for vigorous spring growth.
Clear Away Winter Debris and Inspect for Damage
The first action when the ground thaws is to clear the lawn of accumulated winter debris, including fallen leaves, pine needles, and stray litter. Removing this material is important because a thick layer of debris can mat down the turf, restricting airflow and trapping moisture against the grass crowns.
This matted environment creates ideal conditions for fungal diseases, such as snow mold (Typhula blight). A light raking removes debris and fluffs up matted grass blades, encouraging faster drying and better air circulation to inhibit fungal growth. Cleanup also provides an opportunity to inspect the turf for localized damage that occurred over the winter.
Look closely for damage caused by salt runoff from driveways, which can burn grass blades and inhibit root water uptake. Also, inspect for signs of animal activity, such as vole tunnels or bare patches from pet waste. Identifying these damaged areas now allows for planning necessary spot repairs, like flushing salt-affected areas or patching bare spots later in the season.
Applying Pre-Emergent Weed Control
March is the most important window for applying pre-emergent herbicides, which prevent annual grassy weeds like crabgrass from establishing. These products create a chemical barrier at the soil surface that inhibits cell division in germinating seeds. When a seed attempts to sprout and cross this barrier, it absorbs the herbicide and dies before emerging above the soil line.
Timing is specific: crabgrass seeds germinate once the soil temperature consistently reaches 55 degrees Fahrenheit at a one-inch depth for several consecutive days. Applying the herbicide just before this threshold ensures the barrier is in place for the initial wave of weeds. Since soil temperatures vary widely, applying the product early in March is a proactive measure to catch the earliest germination.
Proper application requires immediate watering to activate the herbicide and set the protective barrier into the top layer of the soil. Pre-emergent products are non-selective, meaning they prevent the germination of all seeds, including desirable grass seeds. If you plan to overseed to thicken your lawn, you must delay the pre-emergent application until new seedlings are well established, or wait until the fall.
Initial Fertilization and Soil Health Checks
As the turf emerges from dormancy, a light initial feeding provides the necessary energy for spring green-up and growth. For cool-season grasses, apply a fertilizer containing slow-release nitrogen, which provides a steady supply of nutrients over several weeks rather than a sudden flush of growth. This measured approach encourages healthy root development rather than excessive top growth. Excessive top growth can deplete the plant’s energy reserves and increase susceptibility to disease later in the year.
The recommended application rate for this first spring feeding should be conservative, targeting between 0.5 to 0.75 pounds of nitrogen per 1,000 square feet. This controlled feeding supports the natural vigorous growth cycle of cool-season grasses, which occurs when temperatures are between 60 and 75 degrees Fahrenheit. Providing a modest nutrient boost prevents the turf from growing too quickly before summer stress hits.
March is also the time to conduct a soil test to understand the lawn’s underlying health. A soil test provides a detailed analysis of the soil’s pH level and concentrations of primary nutrients like phosphorus and potassium. Knowing the pH is useful because grass thrives in a specific range. If the soil is too acidic or alkaline, the turf cannot efficiently absorb available nutrients.
The results from a March soil test guide all subsequent fertilization and amendment decisions for the entire season. For example, if the test indicates a low pH, lime can be applied in March to adjust the acidity and improve nutrient availability. Fertilizer and pre-emergent herbicide application can often be done simultaneously, as many commercial products combine both functions.
Prepare Mowers and Start the Season’s First Cut
Before the grass begins its spring surge, preparing the mowing equipment directly impacts turf health. Sharpening the mower blades is important because a dull blade tears the grass, leaving jagged ends that turn brown and increase disease susceptibility. Ensure the engine is ready by changing the oil, replacing the spark plug, and checking the air filter to prevent mechanical issues during weekly mowing.
The first cut of the season in March should be done at the highest setting recommended for the specific grass type. This initial mowing trims off dead tips, stimulating new growth from the base of the plant. Adhering to the “one-third rule” is fundamental, dictating that no more than one-third of the total blade height should be removed in a single session.
Maintaining a higher cutting height in the early spring encourages the grass to develop a deeper root system. Taller grass blades also shade the soil, keeping the surface cooler and inhibiting the germination of weed seeds. This technique supports the grass’s natural defenses while conserving energy for healthy growth as temperatures climb.