Zoysia grass is a popular warm-season turf known for creating a dense, carpet-like lawn that withstands heat and drought well. Zoysia conducts its primary growth during the hot summer months, unlike cool-season grasses. Providing the correct type and amount of nutrients is necessary to maintain its vibrant green color and promote the density that helps crowd out weeds. A successful fertilization program depends on selecting the proper nutrient ratios and applying them at the right time in the growing season.
Understanding Zoysia’s Primary Nutrient Needs
Zoysia grass is considered a heavy feeder, requiring regular applications of nitrogen (N) to support its dense growth habit and maintain a deep green color throughout the summer months. Nitrogen is the first number listed in the three-number N-P-K ratio on any fertilizer bag and promotes vigorous leaf growth and overall turf density. Because Zoysia is a warm-season grass, it is typically managed with a higher nitrogen ratio compared to cool-season turf.
For established Zoysia lawns, fertilizer ratios often emphasize nitrogen while having lower amounts of phosphorus (P) and potassium (K). Recommended ratios often fall in the range of 3-1-2 or 4-1-2, such as a product with an N-P-K of 15-5-10 or 16-4-8. Phosphorus supports root development and is especially important when establishing a new lawn, but established turf requires very little.
Potassium, the third number, helps the grass manage environmental stresses like drought, heat, and disease. A sufficient potassium level is important for strengthening the grass blades and preparing the turf for winter dormancy. To know the exact amount of phosphorus and potassium your soil needs, conduct a professional soil test every few years. This testing prevents the overuse of nutrients the lawn does not need and allows for the selection of a customized fertilizer ratio.
Selecting the Right Fertilizer Formulation
The best fertilizer formulation for Zoysia grass is a slow-release product, which governs how the nitrogen is delivered to the plant over time. Slow-release nitrogen is typically found in coated granular fertilizers or synthetic organic materials like isobutylidene diurea (IBDU) or sulfur-coated urea. This formulation provides a steady supply of nutrients, which helps prevent the rapid growth surges associated with quick-release products. Sustained feeding is preferred for Zoysia to reduce excessive mowing and minimize the buildup of thatch.
Quick-release fertilizers, containing water-soluble nitrogen sources like ammonium sulfate, offer an immediate nutrient burst and rapid green-up. While useful for correcting color deficiencies, this formulation carries a higher risk of burning the turf, especially in hot weather, and can lead to nutrient leaching. The rapid influx of nitrogen forces top growth at the expense of root development, which ultimately weakens the grass. Many commercial products blend both slow-release and quick-release nitrogen to provide an initial color boost followed by prolonged feeding.
Granular fertilizers are the most common choice, delivering a controlled feed that lasts for several weeks after application. Liquid concentrates can also be used, offering immediate nutrient uptake and are often favored for supplemental, light applications. Regardless of the physical form, the selection should prioritize a formulation where a significant portion of the nitrogen is in the slow-release form to ensure consistent color and health.
Establishing the Seasonal Feeding Schedule
Timing the fertilizer application to coincide with Zoysia’s active growth cycle is necessary for maximizing nutrient absorption and avoiding wasted product. Zoysia should only be fertilized after it has fully emerged from winter dormancy and the soil temperatures are consistently warm. The first application should occur in late spring, typically around May or early June, once the grass is actively growing and the soil temperature has reached about 65°F. Applying fertilizer earlier can prematurely encourage top growth that is susceptible to late frosts and promote weed growth instead of turf growth.
The second feeding should take place during the peak growing season in mid-summer, between July and early August. This application helps maintain the lawn’s density and deep color during the hottest part of the year when the grass is most active. It is recommended to use a slow-release product for this summer application to avoid stimulating excessive growth that could stress the grass in high heat.
A final, lighter application in early fall, around September, is beneficial for strengthening the root system before the grass goes dormant. This late-season feeding should focus on potassium rather than nitrogen to enhance winter hardiness and disease resistance. Stop all nitrogen applications well before the first expected frost, as stimulating new growth too late in the year can deplete the grass’s energy reserves and make it vulnerable to winter injury.