Zoysia grass is a popular warm-season turfgrass, valued for its dense, carpet-like appearance and strong drought tolerance. Successful maintenance relies on precise fertilization timing, which must align with the grass’s periods of dormancy and active growth. Applying nutrients at the wrong time wastes product, promotes weed growth, and can damage the lawn.
Understanding Zoysia’s Growth Cycle and Indicators
The fundamental reason for precise timing lies in the grass’s metabolic state. As a warm-season grass, Zoysia remains biologically inactive during cooler months, turning straw-brown when dormant. Fertilizing during dormancy is ineffective because the roots are not actively absorbing nutrients, leading to wasted product and runoff.
The primary indicator for active growth is sustained soil temperature, not air temperature. Root and shoot growth starts when the soil temperature consistently reaches 65°F to 70°F. Applying nitrogen too early feeds spring weeds and encourages tender top growth susceptible to late frost damage.
Spring Green-Up: The First Application
The first fertilizer application is the most important timing decision. It must be delayed until the Zoysia lawn has achieved at least 75% to 100% green-up, confirming the grass has broken dormancy and its root system is fully active. This window typically falls in late spring, often late May or early June.
The initial feeding should be a complete fertilizer, containing nitrogen (N), phosphorus (P), and potassium (K) in a balanced ratio (e.g., 3-1-2 or 4-1-2). This balanced profile stimulates root and shoot growth following the dormant period. Apply approximately 0.5 pounds of actual nitrogen per 1,000 square feet of turf. Using a slow-release nitrogen source provides a steady supply of nutrients, helping to avoid a sudden surge of top growth.
Sustaining Growth: Mid-Season Feeding
Once the Zoysia lawn is fully green and actively growing, the focus shifts to sustaining growth through the peak summer season. Maintenance applications should be scheduled every four to six weeks during the hottest months (late June through mid-August).
Mid-season applications can increase the nitrogen rate to between 0.5 and 1 pound of actual nitrogen per 1,000 square feet, especially on sandy soils or frequently irrigated lawns.
The final nitrogen fertilizer application must be no later than mid-August. Applying nitrogen past this point encourages soft, new growth easily damaged by cold weather, delaying the hardening process required for winter survival.
Instead of nitrogen, the final application should focus on potassium (K), which enhances cold weather hardiness and disease resistance. This high-potassium, zero-nitrogen application should be timed four to six weeks before the first expected frost date. Potassium strengthens the grass’s cell walls, preparing it to endure dormancy.
Fertilization Schedule for New Zoysia Installations
Newly established Zoysia (from sod, plugs, or seed) requires a cautious fertilization approach.
Sod
For newly laid sod, delay the initial fertilizer application until the pieces are visibly rooted into the native soil, typically two to three weeks after installation. This first feeding should be a light, fast-release product to encourage immediate root anchoring.
Plugs
When establishing Zoysia from plugs, incorporate a starter fertilizer, often high in phosphorus, into the soil before planting. After the plugs are set, they require very light, frequent applications of nitrogen (as little as 1 pound of actual nitrogen per 1,000 square feet every four weeks) during the establishment period. This schedule encourages lateral spread without overwhelming immature root systems.
Seed
Zoysia established from seed focuses on rooting nutrients during the initial germination phase (when soil temperatures are reliably between 65°F and 70°F).
For all new installations, the goal is to promote rooting and lateral spread over rapid top growth. Adjust the nutrient ratio until the turf is fully dense and mature, then transition to the maintenance schedule.