When to Fertilize St. Augustine Grass

how do I make my st augustine grass thicker

St. Augustine grass is a popular choice for lawns in North Texas due to its ability to withstand the region’s hot and humid climate. To keep your St. Augustine lawn lush, green, and healthy, proper fertilization is essential.

However, knowing when to fertilize is a bit tricky, as the timing varies based on factors such as weather conditions and the specific needs of your lawn. In this article, we will provide a seasonal guide to help you determine when to fertilize St. Augustine grass in North Texas.

Understanding St. Augustine Grass Nutrient Needs

Before diving into the specific timing of fertilization, it’s crucial to understand the nutrient requirements of St. Augustine grass. Like all plants, St. Augustine needs three primary macronutrients: nitrogen (N), phosphorus (P), and potassium (K). Nitrogen promotes healthy leaf growth. Phosphorus aids in root development. Potassium enhances overall plant health and stress tolerance.

It’s important to note that St. Augustine grass typically requires more nitrogen than other warm-season grasses. However, excessive nitrogen application can lead to issues like thatch buildup or increased vulnerability to pests and diseases. Choosing the right fertilizer and applying it at the correct time will help ensure your lawn’s optimal health.

Find out more about maintaining St. Augustine turfgrass.

 lawn fertilization schedule for st augustine
Broadcast spreader for spreading granular lawn fertilizer.

Early Spring: The First Application

As North Texas transitions from winter to spring, the temperature begins to rise, and St. Augustine grass starts coming out of its dormant phase. Early spring is an ideal time for the first fertilizer application, usually around late February to early March.

Choose a slow-release fertilizer with a nitrogen-phosphorus-potassium ratio of around 3:1:2 or 4:1:2. Slow-release fertilizers provide a steady supply of nutrients to the grass over an extended period, promoting controlled growth and reducing the risk of Nitrogen runoff.

Apply the first round of fertilizer at a rate of 1 pound of nitrogen per 1,000 square feet of lawn. Be sure to follow the manufacturer’s instructions for proper application techniques.

Late Spring: The Second Application

In late spring, as temperatures continue to rise and St. Augustine grass is actively growing, it’s time for the second fertilizer application. This typically occurs in late April to early May.

Choose a balanced slow-release fertilizer with a nitrogen-phosphorus-potassium ratio of around 3:1:2 or 4:1:2, similar to the first application. Apply the fertilizer at a rate of 1 pound of nitrogen per 1,000 square feet of lawn. This second application will help sustain healthy growth and enhance the overall vigor of your St. Augustine grass.

Summer: Mid-Season Boost

fertilize st augustine in fall
Lush, summer lawn.

The scorching summer temperatures in North Texas can put stress on St. Augustine grass. To help your lawn withstand the heat and maintain its lush appearance, consider a mid-season fertilizer application around late June or early July.

Opt for a slow-release fertilizer with a balanced nitrogen-phosphorus-potassium ratio of around 3:1:2 or 4:1:2. Apply at a lower rate than the previous applications, around 0.5 to 0.75 pounds of nitrogen per 1,000 square feet.

Additional nutrients during this period will support the grass’s health, especially its root system, and aid in drought resistance.

Late Summer to Early Fall: Preparing for Dormancy

As summer transitions to fall, St. Augustine grass naturally slows down its growth in preparation for the dormant period. Fertilizing during this period should focus on maintaining root strength and overall plant health.

Around sometime from late August through Mid October. Use a slow-release fertilizer with a nitrogen-phosphorus-potassium ratio of 3:1:2 or 4:1:2, similar to the previous applications. Apply at a reduced rate, around 0.5 to 0.75 pounds of nitrogen per 1,000 square feet. This application will provide the necessary nutrients to sustain the grass throughout the winter and promote early spring re-growth.

prep lawn for fall
Dandelions are a common weed found in North Texas.

Other Considerations

In addition to seasonal fertilization, some additional factors may impact your St. Augustine grass’s fertilization needs:

Soil Testing: Periodic soil testing will provide valuable information about your lawn’s nutrient levels and pH balance, helping you adjust fertilization practices accordingly.

Watering and Irrigation: Adequate watering practices, such as deep watering and following local watering restrictions, will optimize fertilizer absorption and minimize nutrient leaching.

Weed Control: Maintaining a weed-free lawn is crucial for St. Augustine grass’s health and vitality. Consider using pre-emergent herbicides in conjunction with proper fertilization to prevent weed growth. Read about common weeds found in North Texas.

This is a great time of year to schedule a fall clean-up service. 


Fertilizing St. Augustine grass in North Texas requires a seasonal approach, adjusting nutrient applications to meet the grass’s changing needs throughout the year. By following the guidelines outlined above for early spring, late spring, summer, and late summer to fall, your St. Augustine lawn will remain vibrant, resilient, and the envy of the neighborhood.

Remember to always read and follow the instructions provided by the specific fertilizer product you choose. If you have doubts or need guidance, contact us for personalized lawn fertilization advice.

Picture of M Valdivia

M Valdivia

Leave a Reply

Your email address will not be published. Required fields are marked *

For security, use of Google's reCAPTCHA service is required which is subject to the Google Privacy Policy and Terms of Use.

I agree to these terms.

This site uses Akismet to reduce spam. Learn how your comment data is processed.