When To Fertilize St Augustine In Texas

Knowing when to fertilize St Augustine in Texas is the single most important factor for a thick, green, and healthy lawn. Get the timing wrong, and you risk wasting money, encouraging weeds, or even damaging your grass. This guide cuts through the confusion to give you the optimal schedule for your specific part of the state.

St. Augustine grass thrives in Texas heat but has specific nutritional needs. Feeding it at the right moments supports strong roots, lush growth, and better resistance to drought and disease. Let’s break down the ideal calendar for your lawn care.

Your fertilization schedule is dictated by where you live in Texas. The state’s three main climate zones—North, Central/South, and the Gulf Coast—each have a slightly different ideal timeline. The goal is to feed the grass when it’s actively growing, not when it’s dormant.

Understanding Your Texas Growing Zones

Texas is big, and weather varies greatly. Here’s a quick overview:

North Texas: Colder winters, later spring start, earlier fall frost. Cities include Dallas, Fort Worth, and Wichita Falls.
Central & South Texas: Longer growing season, milder winters. This includes Austin, San Antonio, and the Hill Country.
Gulf Coast & Southeast Texas: Warm, humid, longest growing season. Houston, Beaumont, and Corpus Christi are in this zone.

The Optimal Fertilization Schedule by Region

Follow this general calendar, but always watch your lawn’s actual growth and local weather conditions.

North Texas Schedule

In North Texas, you typically apply fertilizer 3-4 times per year.

First Application (Spring): Apply when soil temperatures consistently reach 65°F, usually late April to early May. Don’t fertilize too early, as it can force tender growth that a late frost might damage.
Summer Application(s): Apply again in early June and optionally in early July. Use a slow-release formula to provide steady nutrients during the peak heat.
Fall Application: This is a crucial feeding. Apply in early September, about 6-8 weeks before your first expected frost. This helps the grass store energy for winter and green up faster in spring.

Central & South Texas Schedule

This region can support 4-5 applications due to the longer season.

Spring Start: Begin in mid to late April, once the grass is fully green and actively growing.
Summer Feedings: Apply in late May, early July, and possibly early August. Space applications 6-8 weeks apart.
Final Fall Feeding: Apply in mid to late September. This late-season feeding is vital for root development before winter dormancy.

Gulf Coast Schedule

The humid Gulf Coast has the most flexible schedule, often 4-5 times from spring to fall.

Early Spring: You can often start as early as March if the grass is growing. Wait for consistent green-up.
Regular Summer Intervals: Fertilize every 6-8 weeks through the summer, ending the summer cycle in August.
Important Fall Feed: Apply in late September or even early October. The warm soil temperatures here allow roots to remain active longer, benefiting greatly from this last feeding.

What Type of Fertilizer Should You Use?

Choosing the right product is as important as timing. Look for a fertilizer specifically formulated for St. Augustine grass.

Nitrogen (N): The most important nutrient for green, leafy growth. St. Augustine needs a steady supply.
Phosphorus (P): Supports root development. Most Texas soils have adequate phosphorus, so a low-middle number (like 5) is often sufficient.
Potassium (K): Promotes overall plant health, drought tolerance, and disease resistance. Crucial for surviving Texas summers.

A great ratio for St. Augustine is something like 15-5-10 or 18-6-12. Always opt for a slow-release nitrogen source. It feeds the lawn gradually over 6-8 weeks, prevents burning, and reduces nutrient runoff.

Step-by-Step: How to Apply Fertilizer Correctly

Doing it right ensures your grass gets the full benefit.

Mow First: Mow your lawn a day or two before you plan to fertilize.
Check the Spreader: Ensure your broadcast or drop spreader is clean and calibrated. The rate is on the bag—do not guess.
Apply Evenly: Overlap your passes slightly to avoid streaks of too much or too little fertilizer. Missed spots can lead to uneven color.
Water Thoroughly: After applying, water the lawn lightly. This helps wash the granules off the grass blades and into the soil where they can start working. You don’t need to soak it, just a good quarter-inch of water.

Key Signs Your Lawn Needs Fertilizer

Besides the calendar, your grass will tell you when it’s hungry. Watch for these signals:

Pale green or yellowish color instead of a deep green.
Slower growth, requiring less frequent mowing.
Thinning turf where soil becomes easily visible.
Poor recovery from foot traffic or stress.

Common Mistakes to Avoid

A few errors can set your lawn back. Here’s what to steer clear of:

Fertilizing Too Early in Spring: This is the most common mistake. It wastes fertilizer and can harm the grass.
Over-Fertilizing (Burn): More is not better. It can salt the soil, burn the roots, and cause excessive thatch buildup.
Fertilizing in Drought or Dormancy: Never fertilize a brown, dormant lawn in summer drought or winter. It cannot use the nutrients and may encourage weeds.
Ignoring Soil Health: Consider a soil test every few years. It will tell you exactly what your soil lacks, preventing you from adding unneeded nutrients.

Seasonal Lawn Care Tips Beyond Fertilizing

Fertilizer is just one piece of the puzzle. For a truly healthy lawn, integrate these practices.

Spring

Apply a pre-emergent herbicide in late winter/early spring to prevent weeds like crabgrass.
Dethatch if the layer between grass and soil is thicker than half an inch.
Set your mower high—3 to 4 inches for St. Augustine. Taller grass shades roots and conserves water.

Summer

Water deeply and infrequently, aiming for about 1 inch per week, including rainfall. Early morning watering is best.
Watch for signs of chinch bugs or gray leaf spot, common St. Augustine pests and diseases.
Avoid heavy nitrogen applications in peak summer heat to reduce stress.

Fall

Continue mowing as long as grass is growing.
This is the best time to aerate compacted soil, allowing water and nutrients to reach the roots better.
Keep applying your pre-emergent in fall to target winter weeds like poa annua.

Winter

Your lawn is mostly dormant. Limit foot traffic on frosted grass, as the blades are brittle and can break. This is a good time to service your mower and other lawn equipment so their ready for spring.

FAQ: Your Texas St. Augustine Fertilization Questions

Can I fertilize St. Augustine in October?

In Central, South, and Gulf Coast Texas, a late September or early October application is highly beneficial. In North Texas, early September is safer to avoid promoting growth right before a frost.

What is the best winter fertilizer for St. Augustine?

Do not fertilize in winter. The grass is dormant and won’t use it. The last fall feeding is your “winterizer.” Some winterizer products are just a late-season fall fertilizer with potassium.

How often should I fertilize my lawn in Texas?

For St. Augustine, 3-5 times per year depending on your region, as outlined above. More is not better and can harm your lawn and the environment.

Is it too late to fertilize in September?

September is actually the ideal time for the important fall fertilization across most of Texas. It’s one of the most important applications of the year.

Should I water after fertilizing?

Yes, a light watering is crucial. It moves the fertilizer into the soil and prevents it from sitting on the grass blades, which could cause burn.

By following this regional schedule and paying attention to your lawn’s condition, you’ll provide your St. Augustine with exactly what it needs, exactly when it needs it. The result is a resilient, beautiful lawn that can handle the unique challenges of the Texas climate. Remember, consistency with proper mowing, watering, and feeding is the real secret to success.