St. Augustine grass, a popular warm-season turf, is known for its thick, carpet-like appearance, but it demands specific conditions to thrive. Meticulous soil preparation completed before installation is essential for this high-maintenance grass to reach its full potential. The success of a new St. Augustine lawn, whether installed as sod or plugs, is entirely dependent on establishing an optimal environment for its roots to quickly take hold. Neglecting these foundational steps can lead to poor establishment, slow growth, and susceptibility to disease and pests.
Site Clearance and Initial Assessment
The first physical step involves completely clearing the existing surface down to the bare soil. This requires removing all unwanted vegetation, including weeds, old turf, and any plant debris that may interfere with the new grass’s root system. Applying a non-selective herbicide several weeks before installation can effectively kill existing plant life, making physical removal easier.
Once the vegetation has died back, strip it away using a sod cutter, shovel, or heavy-duty rake. The area must also be cleared of any rocks, construction debris, or large roots, which impede tilling and create uneven spots in the final lawn. Confirm that the entire area is free of obstructions and the soil is exposed and ready for manipulation.
Soil Testing and pH Adjustment
Understanding the chemical makeup of the soil precedes any physical amendments. A professional soil test provides data on nutrient levels, soil composition, and the current pH level. St. Augustine turf prefers a slightly acidic to neutral reaction, with an optimal pH range generally falling between 6.0 and 7.5.
To collect a representative sample, take small soil cores from multiple spots across the area, typically to a depth of six inches. Mix these samples together and send a small amount to a laboratory for analysis and amendment recommendations. Maintaining the correct pH is important because it controls nutrient availability; roots cannot efficiently absorb essential elements if the soil is too acidic or too alkaline.
If the pH is below the ideal range, apply agricultural lime to raise the level and reduce acidity. Conversely, if the soil is too alkaline, incorporate elemental sulfur to gently lower the pH. Spread these pH-correcting materials evenly over the surface and work them in deeply during tilling. Applying them before tilling ensures uniform distribution throughout the root zone, allowing time for the adjustments to react fully.
Tilling, Grading, and Drainage Correction
With chemical amendments applied, the next step involves physically manipulating the soil structure to prepare for root growth. The soil must be tilled or cultivated four to six inches deep to relieve compaction and promote aeration. Tilling breaks up dense layers, allowing grass roots to penetrate easily and enabling water and air to move freely. This is also the stage where organic matter, such as compost or aged manure, can be incorporated to improve soil structure and enhance moisture retention.
Immediately following tilling, the area must be properly graded to ensure effective surface water drainage. Since St. Augustine grass is susceptible to disease and rot when sitting in standing water, a slight slope away from structures is required. A recommended grade is often a one-inch drop for every eight to ten feet moving away from the house.
The final step is leveling the surface by raking and lightly rolling the tilled soil. The surface must be smooth and even, eliminating low spots where water might pool after irrigation or rain. The soil level should sit about one inch below adjacent sidewalks or driveways so the finished sod or plugs will sit flush with the hardscape.
Pre-Laying Fertilization and Final Preparation
The final steps before installation focus on providing immediate nutrition and ensuring optimal conditions for root establishment. Spread a starter fertilizer, formulated to be high in phosphorus, across the leveled soil surface. Phosphorus is necessary for robust root development and helps the new turf quickly establish a strong foundation in the soil.
Apply the fertilizer according to the manufacturer’s directions and lightly water it into the top layer of soil. Afterward, lightly roll or tamp the soil down to create a firm, smooth surface free of air pockets. This ensures the new sod or plugs will have immediate and complete contact with the prepared soil beneath them.
The last step is a final, light moistening of the soil just before laying the turf. Dampening the soil without oversaturating it creates a receptive bed for the grass roots. This slight moisture encourages delicate root hairs to venture into the prepared soil immediately upon contact, promoting rapid establishment.