When To Fertilize St Augustine Grass In Central Florida

Knowing when to fertilize St Augustine grass in Central Florida is the single most important factor for a thick, green lawn. Get the timing wrong, and you risk weak growth, disease, or environmental harm. This guide cuts through the confusion to give you the optimal schedule for your yard.

Central Florida’s unique climate, with its long growing season and occasional frosts, demands a specific approach. We’ll break down the yearly calendar, explain why timing matters, and give you clear steps to follow. Let’s get your lawn on track for success.

Your fertilizing schedule revolves around the grass’s growth cycles, not the calendar month. St. Augustine thrives in warm soil. The golden rule is to fertilize only when the grass is actively growing and never when it is dormant (brown).

Understanding Central Florida’s Growing Season

Central Florida’s season is long, but it has distinct phases. St. Augustine usually begins it’s growth in early to mid-spring and slows down in late fall.

Spring Green-Up: This is your starting signal. When nighttime temperatures consistently stay above 65°F and you see steady green growth, it’s time for the first application.
Peak Summer Growth: Grass grows fastest in the summer heat. This is when it needs regular nutritional support to stay healthy under stress from heat, rain, and foot traffic.
Fall Slow-Down: As daylight shortens and nights cool, growth slows. Your final fertilization must occur early enough to be used by the grass before dormancy.
Winter Dormancy: The grass turns brown after a frost or prolonged cold. Do not fertilize during this period.

The Optimal Fertilization Calendar

Here is a reliable, year-round schedule for most of Central Florida, including areas like Orlando, Tampa, and Lakeland.

First Application: Early to Mid-April

Apply your first fertilizer around April. Wait until the last frost chance has passed and your lawn has completely exited winter dormancy. This feeding kickstarts growth for the lush season ahead.

Second Application: Early June

A early summer feeding supports vigorous growth. It helps the lawn recover from any late spring stress and prepares it for the intense summer heat. Ensure your lawn is receiving adequate water at this time.

Third Application: Early August

This midsummer application sustains color and density. It strengthens the grass to better resist common summer issues like chinch bugs or fungal diseases. Always check for pest problems before fertilizing.

Final Application: Early to Mid-September

Your last fertilization should occur no later than September 15th. A fall fertilizer helps the lawn recover from summer and builds nutrient reserves in the roots for a stronger spring green-up. Avoid late fall applications, as they can promote tender growth vulnerable to cold damage.

Choosing the Right Fertilizer

Not all lawn fertilizers are created equal. Using the wrong type can damage your St. Augustine.

NPK Ratio: Look for a ratio like 15-0-15, 16-0-8, or similar. St. Augustine needs potassium (the third number) for stress resistance. Avoid high-phosphorus fertilizers unless a soil test shows a deficiency.
Controlled-Release Nitrogen: This is crucial. It feeds the grass slowly over time, preventing a surge of weak growth and reducing nutrient runoff into our waterways.
Iron Supplements: For a deeper green without excessive growth, consider a fertilizer with iron or a separate iron application, especially in the summer.

Essential Steps for Applying Fertilizer

Doing it correctly ensures the grass gets the food and protects the enviroment.

Test Your Soil: A soil test from your local county extension office is the best investment. It tells you exactly what nutrients your lawn lacks.
Mow Beforehand: 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: Calibrate your broadcast or drop spreader according to the bag’s settings. This prevents over or under-application.
Apply Evenly: Walk at a steady pace, overlapping slightly to avoid streaks. Fill the spreader on a driveway or sidewalk to avoid spills on the grass.
Water Thoroughly: Lightly water the lawn after application. This washes the fertilizer off the grass blades and into the soil, where it’s needed.

Critical Mistakes to Avoid

Steering clear of these errors will save you time, money, and a lot of lawn trouble.

Fertilizing Too Early: Feeding dormant grass forces new growth that can be killed by a late frost, wasting fertilizer and weakening the plant.
Fertilizing Too Late: Applications after October promote growth that won’t harden off before winter, leading to cold damage and potential disease.
Over-Fertilizing: More is not better. Excess fertilizer, especially nitrogen, burns grass, pollutes water, and leads to thatch buildup and disease.
Ignoring County Bans: Many Central Florida counties have “summer blackout” periods where nitrogen fertilizer cannot be used (typically June 1 – Sept 30). Always check your local ordinances. You can often use potassium-only or iron products during this time.

Integrating Other Lawn Care Practices

Fertilizing works best when combined with good overall care. Your lawn’s health depends on more than just food.

Watering Wisely

Water deeply but infrequently, aiming for about 3/4 to 1 inch of water per week, including rainfall. Early morning watering is best to reduce evaporation and fungal disease. Overwatering can be just as detrimental as underwatering.

Mowing Correctly

Keep your St. Augustine at a tall height—3.5 to 4 inches. Taller grass shades roots, conserves moisture, and outcompetes weeds. Never remove more than one-third of the grass blade in a single mowing. Keep those mower blades sharp for a clean cut.

Managing Thatch and Weeds

A healthy, well-fertilized lawn is the best weed prevention. If thatch exceeds 1/2 inch, consider dethatching in early spring. Apply pre-emergent herbicides for weeds like crabgrass in late winter, but be careful not to use them when you plan to overseed.

FAQ: Your Fertilization Questions Answered

Can I fertilize St. Augustine grass in October?
It is not recommended in Central Florida. The cut-off date is generally mid-September. Late fertilization can disrupt the grass’s natural dormancy preparation.

What is the best winter fertilizer for St. Augustine?
Do not fertilize in winter. The grass is dormant and cannot use the nutrients. Focus on weed control and minimizing foot traffic on frosty grass.

Should I fertilize after heavy rain?
It’s best to wait if the ground is saturated. Applying to wet grass can cause clumping and uneven distribution. Wait for a drier day if possible.

How often should you fertilize St. Augustine in Florida?
Typically 3-4 times per year, following the spring-summer-fall schedule outlined above. More frequent applications are usually unnecessary and can be harmful.

Is it ok to fertilize a lawn that has weeds?
You can, but you may be feeding the weeds too. For best results, address major weed problems first or use a “weed and feed” product specifically labeled for St. Augustine, applying it at the correct time for the weed type.

Following this optimal timing guide takes the guesswork out of lawn care. By feeding your St. Augustine grass when it’s ready to eat, you promote a resilient, beautiful lawn that can better withstand the challenges of the Central Florida climate. Remember, a consistent, thoughtful approach always beats quick fixes. Your lawn will thank you with lush, green beauty season after season.