Best Fertilizer for St. Augustine Grass: When and What to Apply

Fertilizing your lawn is often associated with one key goal: making the grass greener. While fertilizer can certainly deepen color and help a lawn look fuller, growing a healthy St. Augustine lawn takes more than simply spreading nutrients across the yard.

St. Augustine is a warm-season grass that grows most actively when temperatures rise in spring and summer. During this growing season, the turf requires the right balance of nutrients, proper timing, and supportive lawn care practices to thrive. Applying the wrong fertilizer or fertilizing at the wrong time can lead to uneven growth, weeds, pest pressure, and disease problems.

Many homeowners focus only on fertilizer numbers on the bag. In reality, timing applications throughout the year, maintaining soil health, and supporting the lawn’s root system are just as important.

In this guide, you will learn how to fertilize St. Augustine grass properly, when to apply nutrients, and how to avoid common fertilizing mistakes. We will also explain how fertilizer works alongside weed control, pest management, and new lawn establishment so it stays green, dense, and healthy.

Key Takeaways

• Fertilizing St. Augustine grass is most effective when timed with its growing season, which typically begins in spring as temperatures warm and continues through summer.
• Nitrogen promotes green color and growth, phosphorus supports root development, and potassium improves stress tolerance, making balanced nutrients essential for healthy turf.
• Following a seasonal fertilizing schedule helps prevent problems, with lighter feeding in spring, steady nutrition in summer, potassium in fall, and no fertilizer during winter dormancy.
• Common fertilizing mistakes such as applying too much nitrogen, fertilizing during dormancy, or spreading fertilizer unevenly can weaken the lawn and increase pest or disease issues.
• For new lawns or bare areas, planting St. Augustine grass plugs with starter nutrition like NutriPod can support early root growth and help the lawn fill in over time.

Understanding What St. Augustine Grass Needs From Fertilizer

St. Augustine grass grows vigorously when temperatures rise, which is why proper nutrition is essential during the growing season. Fertilizer supplies nutrients that support blade growth, root development, and the overall turf health.

Unlike cool-season grasses that grow most actively during cooler spring and fall temperatures, St. Augustine grass lawns rely heavily on nutrients during warm months. When temperatures warm in spring, typically ranging between 80 and 95°F, the grass begins actively growing and requires nitrogen and other nutrients to support strong top growth and a dense canopy.

Nitrogen is the most important nutrient for St. Augustine grass. It drives green color and helps produce thicker turf by encouraging new grass blades to grow. However, too much nitrogen can create excessive top growth that weakens the lawn and increases disease problems.

Phosphorus plays a key role in root development. It is particularly important when planting new sod or grass plugs because it helps the root system establish in the soil.

Potassium supports stress tolerance. This nutrient strengthens turf so it can better handle drought, heat stress, and extended periods of high temperatures.

Soil conditions also affect how fertilizer works. Many Florida lawns grow in sandy soils that drain quickly, meaning nutrients can move through the soil faster than in heavier soil types. While a soil test is not always required before fertilizing, it can be a valuable step for understanding your lawn’s needs. Testing reveals soil pH and nutrient levels, helping you choose the right fertilizer instead of relying on guesswork.

Key Nutrients for St. Augustine Grass

When planting new grass plugs, starter nutrition can help support early root growth. NutriPod® grass plug nutrition provides a slow-release 17-1-10 fertilizer formula designed specifically for use during plug planting. The pod sits beneath the plug and releases nutrients gradually for up to 45 days while the root system establishes in the soil.

Seasonal Fertilizer Guide for St. Augustine Grass

Fertilizing St. Augustine grass is most effective when it follows the natural growth cycle of the turf. In Florida and other warm regions such as South Florida and Texas, St. Augustine begins growing actively in spring and continues through summer before slowing again in fall.

Instead of applying fertilizer randomly throughout the year, a seasonal schedule helps maintain healthy turf while preventing nutrient waste.

St. Augustine Fertilizing Schedule

Early Spring Fertilization

Early spring fertilization should begin once temperatures warm consistently and the lawn begins showing signs of active growth. According to The Old Farmer’s Almanac, the first day of spring in 2026 falls on March 20. For warm-season grasses like St. Augustine, it is best to wait until the lawn has fully greened up after winter dormancy and is actively growing before applying fertilizer.

Applying a light nitrogen fertilizer helps the grass recover from dormancy and stimulates new green growth. Avoid fertilizing too early if the turf is still dormant because the nutrients will not be used efficiently.

Late Spring Feeding

Late spring is when St. Augustine grass enters peak growth. During this time, the lawn spreads rapidly, filling thin areas and thickening the turf canopy.

Applying fertilizer across the entire lawn supports strong growth and helps the turf crowd out weeds. Nitrogen-based fertilizers are commonly used during this stage.

Summer Fertilizing Tips

Summer brings the peak temperatures of the year. St. Augustine grass can handle heat, but excessive nitrogen during this time may cause problems.

Instead of high-nitrogen fertilizer, many homeowners use slow-release fertilizer formulas that provide nutrients gradually. This approach helps maintain steady growth while reducing the risk of heat stress. Watering practices also matter during summer. Deep watering supports a stronger root system and helps the turf tolerate drought.

Fall Fertilization

Fall fertilization prepares the lawn for cooler months. A high-potassium fertilizer strengthens the turf and improves stress tolerance as growth slows. Applying potassium during the fall can help St. Augustine grass handle cooler weather and recover more quickly when spring growth begins again.

Winter Lawn Care

During winter, St. Augustine grass typically enters dormancy. Fertilizing dormant grass should be avoided because the lawn is not actively growing and cannot properly use the nutrients.

In some parts of Florida, winters can be mild, and the grass may not go completely dormant. Even so, growth usually slows significantly. During this period, it is still best to avoid fertilizing and focus lawn care on weed control and monitoring for pests instead.

Choosing the Best Fertilizer for St. Augustine Grass

When selecting a fertilizer for St. Augustine grass, the numbers on the bag represent the NPK ratio. These numbers indicate the percentage of nitrogen, phosphorus, and potassium in the fertilizer. Nitrogen is usually the largest component in fertilizer designed for warm-season turf. This nutrient supports green color and leaf growth.

Granular fertilizers are commonly used for lawns because they spread easily and provide slow-release nutrients. Slow release fertilizer formulas release nutrients gradually, helping maintain steady growth without overwhelming the turf. Liquid fertilizers can provide faster results but may require more frequent applications.

High-nitrogen fertilizer is often used during active growth periods, while high-potassium fertilizer may be used to support the lawn during stress conditions such as drought or fall transitions. Another factor to consider is the actual nitrogen application rates. Applying too much nitrogen at once can weaken the turf and increase disease problems.

Recommended Fertilizer Types

When installing SodPods St. Augustine grass plugs such as Citrablue, Floratam, Palmetto, Scotts ProVista, or Seville varieties, starter nutrition helps support root development during the first weeks after planting.

How Fertilizing Wrongly Damages St. Augustine Lawns

Even when homeowners apply fertilizer with good intentions, improper fertilizing can damage the lawn rather than help it.

Applying Too Much Nitrogen

Excess nitrogen can cause excessive top growth that the root system cannot support. When grass grows too quickly, the turf can become weak and more susceptible to pests such as chinch bugs and disease problems, including brown patch or gray leaf spot.

Fertilizing During Dormancy

Fertilizer applied during dormancy often goes unused because the lawn is not actively growing. This can waste nutrients and increase the risk of runoff during rainfall.

Ignoring Soil Test Results

If you choose to run a soil test, it is important to follow the results when selecting fertilizer. Soil pH and nutrient levels can vary widely, especially in sandy soils common throughout Florida. Without this information, you may end up applying fertilizer your lawn does not actually need.

Fertilizing During Heat Stress

Applying fertilizer during extended periods of heat stress can weaken the turf and lead to patchy growth. During extreme summer conditions, lawns may need less fertilizer and more water.

Uneven Fertilizer Application

Uneven spreading can cause visible streaks in the lawn where some areas receive too much fertilizer and others receive too little. Using a spreader and applying fertilizer in overlapping passes helps create consistent coverage.

Fertilizer, Weed Control, and Pest Management

Fertilizer does more than promote green color. A well-fed lawn develops thicker turf that naturally prevents weeds from establishing. Dense St. Augustine grass lawns reduce the space where broadleaf weeds can germinate. This is why fertilizing and weed control often work together.

Pre-emergent herbicide is commonly used in early spring to prevent weeds before they appear. It stops weed seeds from germinating in the soil. Post-emergent herbicide may be used later in the season to control weeds that have already grown.

Maintaining strong turf through proper fertilization also helps the lawn resist pests such as chinch bugs and mole crickets. These insects damage grass blades and root systems, causing areas of turf to turn brown. Poorly maintained St. Augustine grass may also be susceptible to diseases such as gray leaf spot, brown patch, and large patch, which often appear as circular yellow or brown areas in the turf.

A balanced lawn care program that includes fertilizing, mowing, watering, and weed control helps prevent many of these problems before they spread.

Fertilizing New St. Augustine Lawns and Grass Plugs

New lawns require a different fertilizing approach compared to established turf. When installing sod or grass plugs, the key goal is supporting root development rather than rapid top growth. Strong root establishment allows the grass to anchor into the soil and begin spreading across the lawn.

Grass plugs are a practical option for homeowners because they allow lawns to be planted gradually. For example, SodPods St. Augustine Floratam grass plugs can be installed in a grid pattern across bare soil, where the plugs expand outward over time as the grass spreads. Other SodPods varieties include:

• Citrablue grass plugs
• Palmetto St. Augustine
• Scotts ProVista
• Seville St. Augustine

Using the right tools can simplify the process. A sod plug tool helps create evenly spaced planting holes quickly and efficiently. A starter fertilizer can also support plug establishment. NutriPod grass plug nutrition pods are designed to sit beneath each plug during planting, releasing nutrients slowly to encourage early root growth during the first several weeks.

Simple Lawn Care Tips to Keep St. Augustine Grass Green

Fertilizer is only one part of maintaining a healthy lawn. Good mowing practices, watering habits, and soil care all contribute to turf health.

Mowing Height Matters

St. Augustine grass performs best when maintained at a higher mowing height, typically between 2 and 4 inches, depending on the variety. Keeping the grass slightly taller helps shade the soil, reduce weed pressure, and protect the root system, which supports a thicker and healthier lawn.

Water Deeply But Infrequently

Deep watering encourages deeper roots and improves drought tolerance. St. Augustine lawns typically need about 1 to 1.5 inches of water per week, including rainfall. Light, daily watering can lead to shallow roots and weaker turf. Instead, water thoroughly but less often so that moisture penetrates deeper into the soil. See our guide on how long to run sprinklers to help measure and apply the right amount of water.

Maintain Proper Soil Health

Maintaining soil health helps the lawn absorb nutrients more efficiently. Watching for signs of nutrient deficiency or excess, along with practices like aeration and proper fertilizing, can help support long-term lawn health.

Grow a Greener St. Augustine Lawn

Fertilizing St. Augustine grass properly is one of the most effective ways to maintain a thick, healthy lawn. Applying nutrients at the right time during the growing season helps promote steady growth, stronger roots, and the deep green color many homeowners want to see across their yard.

Along with seasonal fertilizing, consistent watering, proper mowing height, and good weed control all contribute to a lawn that stays healthy year after year.

If your lawn has thin or bare areas, St. Augustine grass plug trays from SodPods provide a simple way to repair and expand your lawn over time. By planting plugs and following a proper fertilizing schedule, you can gradually fill in your yard and grow a dense St. Augustine lawn that thrives through the season.