Zoysia grass is a popular warm-season turf known for its dense, carpet-like growth and excellent wear tolerance. Like all warm-season grasses, it enters a period of dormancy when temperatures cool, which dictates a specific and carefully timed feeding schedule. Proper fertilization is necessary to maintain its vibrant green color and promote the density that helps it outcompete weeds during its active growth period. Understanding when to feed Zoysia is just as important as knowing what to feed it. This strategic application of nutrients ensures the grass receives what it needs precisely when its biological systems are ready to utilize them.
Required Soil Analysis
Before applying any fertilizer, a comprehensive soil test is the first step to determine your lawn’s specific nutrient needs. This analysis provides a baseline of existing soil composition, eliminating guesswork that leads to over-fertilization or nutrient imbalances. The test reveals the soil’s pH level and the concentrations of phosphorus (P) and potassium (K).
Zoysia grass prefers a slightly acidic to neutral soil environment, thriving best when the pH falls within a range of 6.0 to 7.0. If the soil test indicates a pH below 6.0, lime may be recommended to raise the pH level and increase nutrient availability to the grass roots. Conversely, a high pH might require sulfur application to lower alkalinity.
The soil test also guides the application of phosphorus. While phosphorus encourages strong root development, it is often abundant in established lawns. Applying it unnecessarily can lead to nutrient runoff and environmental issues, so it should only be added if the test indicates a deficiency. Testing every three to four years provides the information needed to adjust the fertilization program and maintain a healthy, balanced soil profile.
The Active Growth Fertilization Schedule
The primary window for fertilizing Zoysia grass occurs during its active growing season, determined by soil temperature, not the calendar date. The first application should be timed after the turf has fully “greened up” in the spring, which typically happens when soil temperatures at a four-inch depth consistently reach 65 degrees Fahrenheit. Rushing this first feeding while the roots are still dormant can waste nutrients and encourage premature top growth that is vulnerable to late frosts or disease.
This initial application usually falls in the late spring or early summer, around late May or early June. Subsequent applications should follow approximately every six to eight weeks throughout the peak growing period. This schedule allows the grass to maintain consistent color and density without promoting excessive, weak growth that can lead to thatch buildup.
Most fertilization programs for established Zoysia involve three to four applications of a nitrogen-heavy product during the summer months. The total amount of actual nitrogen applied over the entire growing season should fall between two and four pounds per 1,000 square feet of turf. Spreading this total amount across multiple applications ensures the grass receives a steady supply of nutrients, which is crucial for maintaining a healthy, vibrant lawn during the heat of mid-summer.
Determining the Right Nutrient Ratios
Zoysia fertilization centers on the three primary macronutrients, represented by the N-P-K ratio on a fertilizer bag. Nitrogen (N) promotes the dense, vibrant green color and vigorous leaf growth. Phosphorus (P) supports root establishment and maturation, but established lawns typically require little to no additional phosphorus unless a soil test indicates a deficiency.
Potassium (K) is important for fortifying the grass against environmental stress, including heat, drought, and disease pressure. A common nutrient ratio for Zoysia during its active growth phase is a high-nitrogen blend with low or zero phosphorus, such as a 16-4-8 or a 15-0-15 formulation. The specific ratio used should always be adjusted based on the results of the initial soil analysis.
Select fertilizers that contain a significant portion of slow-release nitrogen sources, such as sulfur-coated urea or urea formaldehyde. Slow-release formulations meter out the nitrogen over an extended period, preventing the sudden surge of growth caused by quick-release products. This steady feeding minimizes the risk of fertilizer burn, reduces the need for frequent mowing, and avoids the development of excessive thatch.
Preparing the Turf for Winter Dormancy
A distinct and final feeding application is necessary in the early fall to prepare the Zoysia turf for winter dormancy. This event is often referred to as a “winterizer” application, and its timing is calculated not for leaf growth, but for root health and energy storage. This application should occur approximately four to six weeks before the first expected hard frost in the region, typically in early to mid-fall.
The nutrient profile of this late-season feeding must prioritize potassium (K) while significantly reducing or eliminating nitrogen. Potassium aids the grass in building stronger cell walls, which enhances the turf’s tolerance to cold temperatures and improves overall winter hardiness. An application of a high-potassium, low-nitrogen fertilizer, such as a 0-0-50 or a 10-0-20 blend, supports the root system as the grass transitions to its dormant state.
Applying a high-nitrogen fertilizer too late in the season can be detrimental, forcing new top growth that will be easily damaged by frost and depleting the energy reserves needed for spring green-up. The objective of this final application is to ensure that the roots are robust and well-stocked with energy to survive the winter and resume healthy growth when the soil warms again.