Getting that new St. Augustine sod laid down is a big step toward a beautiful lawn. But to get it right, you need to know when to fertilize new St Augustine sod. Timing is everything for healthy growth and strong roots.
Fertilizing too soon can harm the delicate new roots, while waiting too long can leave your grass weak. This guide will walk you through the essential schedule and steps to ensure your investment turns into a lush, green carpet.
When to Fertilize New St Augustine Sod
The most critical rule is to wait until your sod is firmly rooted. This usually takes about 3-4 weeks after installation. You should be unable to lift a corner of the sod easily. Fertilizing before it’s rooted can “burn” the grass and damage the developing root system, which is trying to establish itself in the soil below.
The best time of year to lay and fertilize new sod is during its active growing season. For St. Augustine grass, that’s late spring through summer, when soil temperatures are consistently above 65°F. Avoid laying sod in the peak of summer heat or right before winter dormancy.
Why Timing Your First Fertilizer is So Important
New sod comes with a built-in head start. It’s grown on a farm where it was regularly fed. The soil it’s grown in often contains a starter fertilizer to support it during harvest and transport. Your first job is not to feed it, but to help it drink.
Initial care focuses on water, water, and more water. The fertilizer applied at the farm is used up quickly once the sod is cut. But the roots are not ready to take up new nutrients from your soil yet. Applying fertilizer to roots that can’t absorb it is wasteful and potentially harmful.
The salts in fertilizer can actually pull moisture out of the young roots if they’re not established, a process called fertilizer burn. Waiting for rooting ensures the plant can properly use the nutrients you provide.
The Signs Your Sod is Ready for Its First Feeding
Don’t just mark a date on your calendar. Your lawn will tell you when it’s ready. Perform these simple checks around the 3-week mark:
- The Tug Test: Gently try to lift a corner of a sod piece. If it resists and feels anchored, roots have taken hold.
- Growth Pattern: You should see consistent, even growth across the entire lawn. The seams between sod pieces should be starting to fill in.
- Color and Resilience: The grass should maintain a healthy green color and spring back when walked on, rather than showing footprints.
Choosing the Right Fertilizer for New St. Augustine
Not all lawn fertilizers are created equal. For that first crucial feeding, you need a specific blend.
Starter Fertilizer vs. Regular Lawn Food
A starter fertilizer is high in phosphorus, the middle number on the N-P-K ratio (e.g., 10-20-10). Phosphorus is essential for stimulating strong root development. Many regular lawn fertilizers are high in nitrogen (the first number) to promote green, leafy growth, but they lack the extra phosphorus new sod desperately needs.
Some local ordinances restrict phosphorus use due to environmental concerns, so check your local rules. If you cannot get a phosphorus-rich starter fertilizer, choose a balanced fertilizer (like a 15-15-15) for the first application instead.
Understanding the N-P-K Ratio
The three numbers on a fertilizer bag represent Nitrogen (N), Phosphorus (P), and Potassium (K).
- Nitrogen (N): Promotes vigorous blade and leaf growth, giving that lush green color.
- Phosphorus (P): Critical for root, flower, and seed development. This is the star for new sod.
- Potassium (K): Strengthens the plant, improving its resistance to disease, drought, and cold weather.
Step-by-Step: How to Fertilize Your New Sod
Once your sod passes the tug test, follow these steps for a successful first feeding.
- Mow First: Give your new lawn its first mowing once it reaches about 3.5 inches tall. This encourages the grass to spread and thicken. Ensure your mower blade is sharp to avoid tearing the grass.
- Check the Weather: Apply fertilizer when no heavy rain is forecasted for 24-48 hours. You want the fertilizer to be watered in, but not washed away.
- Measure Your Lawn: Calculate the square footage (length x width) to determine how much fertilizer you need. Over-application is a common mistake that can damage your lawn.
- Use a Spreader: For even coverage, always use a broadcast or drop spreader. Calibrate it according to the bag’s instructions to apply the correct rate.
- Water Deeply: Immediately after applying the fertilizer, water your lawn thoroughly. This helps dissolve the granules and moves the nutrients into the soil where the roots can access them, preventing any potential for burn.
Your Long-Term St. Augustine Fertilization Schedule
After the initial starter feeding, your St. Augustine needs a regular diet to stay healthy. Follow a seasonal schedule.
- Early Spring (March-April): Apply a balanced, slow-release nitrogen fertilizer after the grass has fully greened up and you’ve mowed at least twice. This encourages recovery from winter.
- Late Spring (May-June): This is a key feeding for summer growth. Use a fertilizer formulated for St. Augustine or Southern lawns.
- Summer (July-August): A light summer feeding can help maintain color and strength during heat stress. Avoid high-nitrogen feeds during extreme heat.
- Early Fall (September-October): Apply a winterizer fertilizer that is higher in potassium. This helps the grass build hardiness for the cooler months. Do not fertilize too late in fall, as it can promote tender growth vulnerable to frost.
Remember, St. Augustine grass generally needs about 4 pounds of nitrogen per 1,000 square feet per year, split across these applications. Always follow the specific rates on your product label.
Common Mistakes to Avoid With New Sod
Even with good intentions, its easy to make errors. Here are the big ones to steer clear of.
- Fertilizing at Installation: Resist the urge to feed immediately. The sod farm has already done that. Your focus must be on frequent, light watering.
- Using Weed & Feed Products: Never use a weed-and-feed product on new sod. The herbicides can severely damage or kill the young, tender grass. Wait at least until the lawn has been mowed 4-5 times.
- Overwatering After Feeding: While you need to water in fertilizer, returrn to a deep, infrequent watering schedule afterward to encourage deep roots.
- Ignoring Soil Test: For long-term health, a soil test every 2-3 years is invaluable. It tells you exactly what nutrients your soil lacks, so you don’t guess or over-apply.
FAQ: Your New Sod Fertilization Questions Answered
Can I fertilize new St. Augustine sod after 2 weeks?
It’s not recommended. Two weeks is typically too early for the roots to be fully established. Always perform the tug test first. Waiting the full 3-4 weeks is safer and more effective.
What is the best fertilizer for establishing St. Augustine?
A starter fertilizer with a high phosphorus content (like a 10-20-10 or similar ratio) is best for the first application. This directly supports the critical root growth phase.
How soon after laying sod can I mow?
You can mow once the grass has grown tall enough to be cut without scalping, usually when it reaches about 3.5 inches. This often occurs around the same 3-4 week mark, just before or after your first fertilization.
Should I water sod before fertilizing?
Your sod should be consistently moist during its establishment. It’s best to fertilize when the soil is damp but not soggy, and then water immediately after application to wash the granules off the blades and into the soil.
Why is my new sod turning yellow?
Yellowing can have several causes: lack of water, too much water (drowning the roots), or a nutrient deficiency. Ensure your watering schedule is correct first. If the sod is rooted and yellowing, the first fertilization with a starter fertilizer often corrects the issue by addressing nutrient needs.
By following this essential timing for fertilizing your new St. Augustine sod, you give your lawn the strongest possible foundation. Patience in those first few weeks pays off with a thicker, healthier, and more resilient turf that you can enjoy for seasons to come. Remember, the goal is to work with the grass’s natural growth cycle, not against it. With proper feeding and care, your new sod will quickly become a established, beautiful lawn.