Korean grass, known as Zoysia tenuifolia or Zoysia japonica, offers an appealing solution for various landscaping needs due to its fine texture and impressive drought tolerance. This perennial grass creates a dense, carpet-like appearance, making it a desirable choice for homeowners seeking an attractive and resilient groundcover or lawn alternative. Successfully cultivating Korean grass requires understanding its environmental needs, especially its suitable growing zones, to ensure it thrives and maintains its lush appearance.
Understanding Plant Hardiness Zones
Plant hardiness zones are geographical areas defined by their average annual extreme minimum winter temperatures. The USDA Plant Hardiness Zone Map is the standard reference for gardeners, dividing North America into zones based on 10-degree Fahrenheit increments. Each zone indicates the lowest temperatures a plant can endure. This system provides a framework for selecting plants that are likely to withstand a region’s winter cold.
Hardiness zones help gardeners choose plants that are likely to survive. Plants grown outside their recommended hardiness zone may suffer damage or perish during winter. While these zones primarily address cold tolerance, they are essential for initial plant selection, guiding decisions on what can realistically grow in a specific location.
Where Korean Grass Thrives
Korean grass (Zoysia japonica and Zoysia tenuifolia) thrives across USDA hardiness zones 5 through 11. Zoysia japonica, also known as Japanese or Korean lawngrass, is adaptable and commonly used for lawns. Zoysia tenuifolia, also known as Korean velvet grass or no-mow grass, is characterized by its finer texture and is frequently chosen for ornamental groundcover due to its unique mounding habit.
Zoysia grass is well-suited for warmer climates, thriving where summer temperatures reach 80 to 95 degrees Fahrenheit. While it can survive in colder zones like 5, it experiences a longer period of winter dormancy, turning brown with the first frost and being one of the last grasses to green up in spring. In the warmest zones, Korean grass maintains its green color for a longer period, though some dormancy can still occur during cooler spells.
Essential Growing Conditions Beyond Zone
Successful growth of Korean grass depends on several environmental factors beyond its hardiness zone. Sunlight is essential; Zoysia grass performs best in full sun, meaning at least six hours of direct sunlight daily. It can tolerate some partial shade, especially Zoysia tenuifolia, but its density and vigor may be reduced in heavily shaded areas.
Soil composition and drainage are also important for healthy growth. Korean grass adapts to a wide range of soil types, including sandy, loamy, and clay soils, but it thrives in well-drained conditions. A slightly acidic to neutral soil pH (6.0 to 7.0) is ideal for nutrient uptake. While drought-tolerant once established, consistent watering is necessary during its establishment phase and prolonged dry periods to prevent discoloration. Optimal growth occurs when summer temperatures are above 80°F, as it is a warm-season grass.
Planting and Maintaining Korean Grass
Proper site preparation is important for establishing Korean grass. This involves clearing the area of any debris, rocks, or unwanted vegetation to provide a clean bed for planting. Improving poorly draining or infertile soil by incorporating amendments can improve the grass’s establishment and long-term health. Ensuring good drainage promotes a deeper, more robust root system.
Korean grass can be established using seeds, sprigs, plugs, or sod, with plugs and sod being common methods due to the slow germination of seeds. For plugs, planting them about 4 to 6 inches apart allows the grass to spread and form a dense mat over time. During establishment, consistent moisture is essential; the soil should remain moist, not waterlogged, until the grass is rooted.
Once established, watering can be reduced, about an inch per week during dry periods. Mowing height for Zoysia japonica is maintained at 1 to 1.5 inches, while Zoysia tenuifolia is left unmowed or mowed minimally due to its slow growth and low habit. Fertilization with a complete fertilizer during the growing season supports vigorous growth, and a potassium treatment in the fall can enhance winter hardiness. As a warm-season grass, Korean grass goes dormant and turns brown in cooler winter months.