Zoysia japonica, known as Japanese or Korean lawngrass, is a favored turfgrass option. This warm-season perennial grass is recognized for its durability and adaptability across various climates. It was introduced to the United States in the late 1800s, originating from the coastal grasslands of Southeast Asia.
Key Attributes and Benefits
Zoysia japonica creates dense turf with a medium-coarse leaf texture and a bright green color during its active growing season. It spreads through both rhizomes (underground stems) and stolons (above-ground stems), forming a mat-like, creeping growth habit that contributes to its thick, uniform coverage. This dense growth naturally suppresses weeds by competing for resources and sunlight.
The grass exhibits tolerance to drought, heat, and foot traffic, making it suitable for heavily used areas. Its deep root system allows it to efficiently conserve moisture and withstand dry periods. Zoysia japonica requires less frequent mowing compared to many other turfgrasses due to its slow vertical growth rate. This reduced mowing frequency translates to lower maintenance costs and effort.
Planting and Establishment
Successful establishment of Zoysia japonica begins with proper site preparation. Soil testing is recommended to determine pH levels and nutrient needs, as this grass thrives in slightly acidic to neutral soil with a pH between 6.0 and 7.0. Loosening the top 2 to 3 inches of soil, potentially with a tiller for compacted areas, improves root penetration and water retention. Removing existing vegetation and debris is important to prevent competition with the new grass.
Zoysia japonica can be established using seed, plugs, or sod, each with varying establishment times and costs. While seed is commercially available, it has a lengthy germination rate, typically taking 14 to 21 days or even up to a month, and requires consistent moisture and soil temperatures above 65°F (18°C) for successful germination. Plugs, small pieces of rooted grass, are a budget-friendly option, planted 6 to 12 inches apart and requiring several years for full coverage. Sod provides instant coverage and is the fastest method, though it is generally the most expensive.
The optimal time for planting Zoysia japonica is late spring to early summer, after the last frost and when daily temperatures are consistently in the 70s Fahrenheit. This timing allows the grass a full growing season to establish before winter dormancy. Initial watering is crucial for establishment; the seedbed or newly laid sod/plugs should be kept consistently moist until the grass is rooted, typically requiring daily watering for the first 30 days.
Ongoing Care and Management
Maintaining an established Zoysia japonica lawn involves specific routine practices to promote health and appearance. Mowing frequency can be weekly, especially during the peak growing season, with a recommended cutting height of 1 to 2 inches. Some varieties may be mowed lower, but never remove more than one-third of the leaf blade at any single mowing to avoid stressing the grass. Zoysia grass is known for its tough, stiff blades, so using a sharp mower blade is essential to prevent tearing and yellowing.
Watering should be deep and infrequent once the grass is established, typically requiring about 1 inch of water per week, including rainfall. This encourages deeper root growth and enhances drought tolerance. Watering in the early morning is advised to minimize evaporation and reduce the risk of fungal diseases. Fertilization should be moderate to maintain turf density without excessive growth; a balanced fertilizer can be applied three to five times during the growing season, from late spring to late summer.
Zoysia japonica generally shows good resistance to pests and diseases, but it can be susceptible to Rhizoctonia Large Patch, especially in humid conditions or with excess organic matter. Proper mowing height, morning watering, and thatch control help prevent this disease. Dethatching is a significant management practice for Zoysia, as its dense growth habit can lead to a thick layer of thatch, which is undecomposed grass stems. Lawns should be dethatched when the thatch layer exceeds 1/2 inch, ideally in early summer after the grass has fully greened up.
Important Considerations
Zoysia japonica is a slow-growing grass, which contributes to its low mowing requirements. This also means it has a slower establishment rate compared to other turfgrasses. If the lawn is damaged, recovery will be slower than with faster-growing grasses.
Zoysia japonica has a dormancy period. As a warm-season grass, it turns tan or straw-colored during colder temperatures, typically from mid-fall to mid-spring, and after the first frost. It will green up again with warmer weather, as this seasonal browning is a natural part of its cycle. While its dense growth offers benefits like weed suppression, it also means an excessive thatch layer can accumulate without proper management, potentially leading to disease issues and reduced turf quality.