Knowing when to fertilize zoysia grass is the single most important factor in maintaining a healthy, resilient lawn. Fertilizing zoysia grass at the optimal times supports its dense growth and helps it withstand seasonal stresses.
This guide provides a clear, season-by-season schedule. You will learn the best times to apply fertilizer and why timing matters so much.
We will also cover how to choose the right product and how to apply it correctly. Following this advice will give you a thick, green carpet that crowds out weeds and survives tough conditions.
When To Fertilize Zoysia
The ideal fertilization schedule for zoysia grass is built around its natural growth cycle. Zoysia is a warm-season grass, meaning it grows actively in the heat of summer and goes dormant, turning brown, in cooler weather.
Your goal is to feed it when it can actually use the nutrients. Applying fertilizer at the wrong time wastes product and can harm your lawn.
The core schedule involves two main feeding periods: late spring and mid-summer. Some lawns may benefit from a third, lighter application in early fall. Winter fertilization is not recommended.
The Importance Of Soil Testing First
Before you even buy a bag of fertilizer, you should conduct a soil test. This is a step many homeowners skip, but it is crucial. A soil test tells you exactly what nutrients your lawn soil lacks.
It measures pH levels and key nutrients like phosphorus and potassium. Zoysia prefers a soil pH between 6.0 and 6.5. If the pH is too low (acidic), the grass cannot absorb nutrients effectively, even if you fertilize.
You can get a soil test kit from your local county extension office or a garden center. The results will provide specific recommendations for your lawn, taking the guesswork out of fertilization.
Late Spring: The First And Most Important Application
The first fertilizer application should occur in late spring, after the grass has fully greened up. This is usally when soil temperatures consistently reach about 70°F.
Do not fertilize too early. If you apply fertilizer while the zoysia is still dormant or just beginning to wake up, you will feed winter weeds instead of your grass. Wait until you have mowed the lawn at least twice.
This spring feeding provides the nutrients needed for the rapid growth phase. It helps the lawn recover from winter dormancy and build density for the summer ahead.
- Timing: Late May to early June for most regions.
- Goal: Kickstart growth and encourage thickening.
- Key Nutrient: A balanced fertilizer or one with a slightly higher nitrogen content is ideal.
Mid-Summer: The Second Core Application
The second application comes in the heart of summer, typically around July or early August. This feeding sustains the grass through its peak growing period and the stresses of heat and potential drought.
By mid-summer, the nutrients from the spring feeding have been largely used up. A summer boost keeps the grass growing strongly and maintains its rich green color.
However, be cautious during periods of extreme heat or drought. If your area is under a water restriction or a severe heatwave, it may be better to delay fertilization until conditions improve. Fertilizing a stressed lawn can cause burn.
Adjusting for Heat and Drought Stress
If you are experiencing a very hot, dry summer, consider using a slow-release fertilizer for this application. Slow-release formulas feed the grass gradually over several weeks, reducing the risk of burning the lawn.
Ensure your lawn receives about 1 inch of water per week, either from rainfall or irrigation, after fertilizing. This helps move the nutrients into the soil and prevents the fertilizer granules from sitting on the grass blades.
Early Fall: The Optional Third Application
A light, optional third application can be made in early fall, about 6-8 weeks before your area’s first expected frost date. The purpose of this feeding is not to promote top growth but to strengthen the roots.
Use a fertilizer that is lower in nitrogen but higher in potassium (the third number on the bag). Potassium promotes root development, disease resistance, and winter hardiness. It helps the grass store energy for its dormant period and improves its comeback in the spring.
Do not apply fertilizer too late in the fall. Promoting new, tender growth right before a frost can damage the grass and make it more vulnerable to winter injury.
- Timing: Early to mid-September for many zones.
- Goal: Enhance root strength and winter hardiness.
- Key Nutrient: Potassium (e.g., a formula like 5-10-30).
Understanding Fertilizer Numbers And Types
Choosing the right product is as important as timing. All fertilizer bags display three numbers, like 16-4-8 or 10-10-10. These are the N-P-K ratios, representing the percentage by weight of Nitrogen (N), Phosphorus (P), and Potassium (K).
- Nitrogen (N): Promotes lush, green blade growth and is the most important nutrient for zoysia’s density and color.
- Phosphorus (P): Stimulates strong root development. Many soils already have sufficient phosphorus, which is why a soil test is helpful.
- Potassium (K): Improves overall plant health, stress tolerance, disease resistance, and cold hardiness.
For most zoysia lawns, a balanced fertilizer (like 15-15-15) or one with a higher first number (like 16-4-8) works well for spring and summer. For the fall, switch to a low-nitrogen, high-potassium formula.
Slow-Release vs. Quick-Release Fertilizer
You will also choose between slow-release and quick-release (water-soluble) nitrogen. Slow-release fertilizers feed the grass over an extended period, from 6 to 12 weeks.
They are more expensive but provide a steady nutrient supply, reduce the risk of burning, and require fewer applications. Quick-release fertilizers give the grass a rapid green-up but must be applied more frequently and can easily burn the lawn if not watered in immediately.
For the average homeowner, a slow-release fertilizer is often the best and safest choice, especially if you are not comitted to a frequent feeding schedule.
Step-by-Step Guide To Applying Fertilizer
Proper application ensures your lawn gets the full benefit of the fertilizer. Here is a simple process to follow.
- Mow First: Mow your lawn a day or two before you plan to fertilize. Collect the clippings to ensure the granules reach the soil.
- Check the Spreader: Use a broadcast (rotary) or drop spreader. Calibrate it according to the settings on the fertilizer bag to apply the correct amount.
- Apply Evenly: Walk at a steady pace, slightly overlapping each pass to avoid striping (light and dark lines of grass). Uneven application can cause burning in some spots and under-feeding in others.
- Water Thoroughly: After applying, water the lawn lightly. This washes the fertilizer off the grass blades and into the soil. About a quarter-inch of water is sufficient.
Common Mistakes To Avoid
Even with good intentions, its easy to make errors that hurt your lawn. Avoid these common pitfalls.
- Fertilizing Too Early in Spring: This is the most frequent mistake. It feeds weeds and can cause the zoysia to break dormancy prematurely, risking damage from a late frost.
- Over-Fertilizing: More is not better. Excess fertilizer, especially nitrogen, can burn the grass, pollute waterways, and lead to excessive thatch buildup as the grass grows too quickly.
- Fertilizing a Dormant or Stressed Lawn: Never fertilize brown, dormant zoysia in winter. Also avoid fertilizing during summer drought unless you can irrigate.
- Ignoring Soil pH: If your soil is too acidic, the fertilizer you apply will be largely ineffective. A soil test may recommend applying lime to correct the pH.
Regional Considerations For Fertilization Timing
While the late spring, summer, early fall schedule is a universal guideline, your specific location will fine-tune the exact dates.
Your local climate dictates the length of your growing season. A lawn in Georgia will start growing earlier than one in Kansas.
Transition Zone Challenges
The Transition Zone, which runs through the middle of the United States, presents unique challenges. Here, both warm-season and cool-season grasses can struggle.
For zoysia in the Transition Zone, the window for the first application may be slightly later, as soil warms up more slowly. The fall application is particularly important here to ensure the grass survives colder winters. Pay close attention to soil temperature rather than just the calendar.
Integrating Fertilization With Overall Lawn Care
Fertilization is just one part of a healthy lawn care program. For best results, combine it with proper mowing, watering, and weed control.
Mow your zoysia at the correct height, which is typically between 1 and 2.5 inches. Never cut more than one-third of the grass blade at a time. Proper mowing encourages the dense growth that zoysia is known for.
Water deeply but infrequently, aiming for about 1 inch per week. This encourages deep root growth. Early morning is the best time to water, reducing evaporation and disease risk.
Pre-emergent herbicides for weeds like crabgrass should be applied in early spring, before soil temperatures hit 55°F. Post-emergent weed control is best done when weeds are actively growing, seperated from fertilization by at least a few days.
FAQ: Frequently Asked Questions
Here are answers to some common questions about fertilizing zoysia grass.
Can I Fertilize Zoysia in the Winter?
No, you should not fertilize zoysia in the winter. The grass is dormant and not actively growing, so it cannot use the nutrients. Fertilizing in winter can harm the dormant grass and is a waste of product.
What Is the Best Fertilizer for Zoysia Grass?
The “best” fertilizer depends on your soil test results. A general recommendation is a balanced, slow-release fertilizer with an N-P-K ratio like 15-15-15 or 16-4-8 for spring and summer. For fall, use a fertilizer with less nitrogen and more potassium, such as a 5-10-30 formula.
How Often Should You Fertilize Zoysia?
Most established zoysia lawns do well with 2 to 3 applications per year: one in late spring, one in mid-summer, and an optional one in early fall. Newly sodded or plugged lawns may require more frequent, lighter feedings in their first growing season to encourage establishment.
Is It Too Late to Fertilize Zoysia in October?
In most regions, yes, fertilizing in October is too late. By this time, the grass is preparing for dormancy or is already dormant. Applying nitrogen can stimulate new growth that will be damaged by frost. The cutoff for fall fertilization is typically 6-8 weeks before the first frost, which is often late August or September.
Should You Water Zoysia After Fertilizing?
Yes, you should water your lawn lightly immediately after applying granular fertilizer. This step, called “watering in,” helps dissolve the granules and moves the nutrients into the soil where the roots can access them. It also prevents the fertilizer from burning the grass blades.