The arrival of spring in Alabama signals the “green-up,” when dormant turfgrass begins to turn green. This annual transition dictates the timing for the year’s lawn maintenance schedule. Active growth is not determined by the calendar but by specific environmental conditions. Understanding this biological trigger helps Alabama residents prepare their warm-season turfgrasses, such as Bermuda, Zoysia, and Centipede grass, for the summer heat.
The Role of Soil Temperature in Spring Green-Up
The mechanism signaling warm-season grasses to exit winter dormancy is the sustained warming of the soil, not the occasional rise in air temperature. Homeowners should focus on the temperature at a four-inch soil depth, as this is the reliable indicator for the start of root and shoot activity in turfgrass.
Warm-season grasses like Bermuda and Zoysia require the four-inch soil temperature to consistently reach between 60°F and 65°F to begin active growth. Centipede grass follows this general range for initial greening, though optimal root growth occurs when temperatures climb consistently into the 70s. If the soil warms quickly and then drops due to a late cold snap, the new, tender shoots can be damaged, forcing the plant to use stored energy to recover.
The requirement for soil temperature explains why grass next to a sidewalk or driveway often greens up first; the surrounding concrete absorbs and retains heat more efficiently than the open lawn. A period of warm air temperatures followed by cooler nights will slow the green-up process, as the soil temperature struggles to maintain the necessary threshold. Tracking this underground temperature provides a more accurate forecast for lawn readiness than simply watching the weather forecast.
Geographic Timing: When Grass Starts Growing Across Alabama
Because of Alabama’s length and varied topography, the arrival of consistently warm soil temperatures follows a clear gradient from south to north. Alabama is broadly categorized into three zones for turfgrass management: the Coastal/Southern, the Central/Piedmont, and the Mountain/Northern regions.
Coastal/Southern Region
The Coastal and Southern Alabama region, including Mobile and the Gulf Coast, experiences the mildest winters and the longest growing seasons, sometimes lasting up to 270 days. The 60°F soil temperature benchmark is typically met earliest here, leading to green-up often beginning in late March or the first week of April.
Central Region
Moving into Central Alabama, which includes cities like Montgomery and Birmingham, the green-up timeline shifts slightly later. The soil takes longer to warm up and maintain the necessary temperature due to the slightly cooler winter conditions. Residents in this middle portion of the state can generally expect to see their lawns begin to turn green around mid-April.
Mountain/Northern Region
Northern Alabama, encompassing areas near Huntsville and the Tennessee Valley, sits in a transition zone where the last frost date can be as late as mid-April. The shorter growing season, closer to 180 to 200 days, means the soil warms up last, making this the final area in the state to see widespread green-up. Homeowners in this northern region should anticipate the start of active grass growth in the latter half of April, sometimes pushing into early May.
Post-Green-Up: First Steps for Lawn Care
Once the turfgrass shows consistent new green growth, it signals the beginning of the heavy maintenance season, starting with the first mow of the year. The initial cut should be done as soon as the grass is visibly growing, typically in early to mid-March in the south, following the green-up event. This first mowing is often a “scalping” cut, where the lawn is mowed slightly lower than normal to remove the remaining dormant, brown leaf blades from winter.
Removing this old material allows sunlight and warmth to better penetrate the soil, encouraging more vigorous growth in the new shoots. Wait until the threat of a hard freeze has passed, generally by early April, before performing this lowest cut to avoid damaging the exposed crowns of the plants. Sharpening the mower blade before this task prevents tearing the new grass, which can leave the plant susceptible to disease.
The next immediate task involves managing weeds and providing initial nutrition, which must be timed carefully. While pre-emergent herbicides, designed to stop weed seeds from germinating, should ideally be applied before the soil consistently reaches 55°F, the first light application of fertilizer should wait. Applying a nitrogen-based fertilizer before the grass is actively growing will only feed the emerging weeds rather than the turfgrass. The first fertilizer application should be a light feeding scheduled after the turf has fully emerged from dormancy and is being mowed regularly.