Zoysia grass is a popular choice for lawns across the southern and transition zones of the United States. As a warm-season turfgrass, Zoysia enters dormancy when temperatures drop in cooler months, causing its blades to turn a straw-like brown color. Homeowners anticipate the lawn returning to its vibrant green state. The timing of this transition from brown dormancy to active green growth is dictated by specific environmental cues, not the calendar.
The Essential Temperature Threshold
The single most important factor determining when Zoysia grass wakes up is the temperature of the soil, not the air. While a few warm, sunny spring days may feel encouraging, the turf will not break dormancy until the ground itself has warmed sufficiently. The biological trigger for Zoysia to initiate new growth begins when the soil temperature, measured at a depth of four inches, consistently reaches a range between 55 and 65 degrees Fahrenheit.
Green-up is a gradual process that starts when the soil temperature first reaches approximately 55°F, signaling the plant’s roots to become active. If soil temperatures fluctuate significantly or dip back down due to a late cold snap, the grass’s effort to green up can be stalled or even temporarily reversed. This is why soil thermometers are more accurate predictors of spring growth than simple air temperature readings.
Regional Timing and Climate Factors
Because the green-up process is temperature-dependent, the timing varies significantly across different geographic locations. In the Deep South, where winter is mild, Zoysia may begin to show signs of life as early as March, experiencing a relatively short dormancy period of only one to two months in the warmest zones. Further north, within the Transition Zone, the dormancy period is longer, often lasting three to four months, pushing the start of the greening process into late April or even mid-May.
Local environmental conditions within a single yard can further influence this timing. Areas receiving full, direct sunlight warm up faster than shaded areas, causing the grass there to green up first. For example, soil near sidewalks and driveways often warms more quickly due to radiating heat, creating noticeably earlier green patches. Conversely, a lawn located near a large body of water or in a valley may experience cooler temperatures, delaying the full transition until late May or early June.
Factors That Influence Green-Up Speed
Even after the soil has reached the necessary temperature threshold, several factors can either accelerate or delay the speed and uniformity of the greening process. One common cause of delayed or patchy green-up is a thick layer of thatch, which is the accumulation of organic matter between the soil and the grass blades. This dense layer acts as insulation, preventing the sun’s warmth from penetrating and heating the soil below.
Proactive Measures for Green-Up
For a faster and more uniform spring transition, homeowners can take a few proactive measures. Scalping the lawn—mowing it very low just before the expected green-up—removes the dead, brown winter foliage. This allows sunlight to reach the soil directly and warm it more quickly. Applying a light, early spring fertilizer, typically after about 50 percent of the lawn has turned green, provides the necessary nutrients to support the new growth.
Risks to Green-Up
An unseasonal cold snap after the grass has started to green can damage the tender new shoots. This results in temporary burn-back and a visible delay in the full return to a lush, green appearance.