Sodding, the process of installing pre-grown rolls or squares of turfgrass, offers an immediate lawn solution that bypasses the long wait time of seeding. This instant lawn, however, is a living organism that has been severed from its established root system and requires immediate support to survive. The success of a new sod installation largely depends on how quickly the grass can anchor itself into the underlying soil. Preparing the ground with the correct nutrients just before laying the sod is a foundational step to ensure this rapid establishment.
The Critical Role of Starter Fertilizer
Applying fertilizer to the prepared soil directly before installation promotes the successful transition of the turf. New sod experiences stress, sometimes called transplant shock, when it is harvested, transported, and laid in a new environment. A specialized fertilizer application provides readily available nutrients directly to the root zone, helping to mitigate this shock. The primary goal is to encourage the grass to develop new, vigorous roots that quickly grow down into the native soil.
This early support facilitates the fusion of the existing root mat with the prepared grade beneath it. Prompt root establishment is necessary because it improves the sod’s ability to draw water and stabilize itself against environmental factors. Relying solely on the sod’s limited nutrient reserves may not be sufficient for rapid root growth, and feeding the roots through the dense sod layer after installation is less effective.
Selecting the Ideal Nutrient Composition
The type of fertilizer used for pre-sod application is known commercially as a starter fertilizer, distinct from that used on an established lawn. This formulation prioritizes phosphorus (P), the middle number in the N-P-K ratio, because phosphorus directly supports energy transfer for root development. Look for a product where the middle number is high, such as ratios like 10-20-10, 16-16-16, or 12-24-12. Since phosphorus is relatively immobile in the soil, applying it directly beneath the sod ensures developing roots can access it immediately.
Avoid fertilizers that contain a high percentage of nitrogen (N), the first number in the ratio, during this phase. High nitrogen promotes lush, green leaf growth, encouraging the plant to use energy on top growth rather than root growth. Excessive top growth before root establishment can weaken the sod and increase its susceptibility to drought or disease. Favoring a phosphorus-rich blend directs the plant’s energy toward building a deep, resilient root system.
Proper Application Timing and Technique
The optimal timing for applying the starter fertilizer is immediately before the sod is laid down, after the final grading and soil preparation are complete. This positions the nutrients precisely where the roots will begin to grow into the soil. The application rate must strictly follow the product instructions, often calculated to deliver approximately 0.5 to 1 pound of actual nitrogen per 1,000 square feet. Use a broadcast or drop spreader to ensure the granular fertilizer is distributed evenly across the entire area, preventing streaks or patches of over-fertilization.
After spreading, lightly incorporate the fertilizer into the top one to three inches of the prepared soil using a rake or light tiller. This mixes the phosphorus, which has low soil mobility, into the layer where the sod roots will first appear. Once the fertilizer is applied and worked in, the sod can be installed directly over the treated area. If the soil is particularly dry, a light watering after application may help dissolve the granules, but avoid making the soil too muddy for installation.
Essential Post-Installation Care
Immediately following the installation of the sod, a thorough, deep watering is essential. The goal is to saturate the sod and the underlying soil to a depth of at least three to four inches. This prevents the roots from drying out and encourages the immediate connection between the sod and the prepared grade. This initial watering must be done within 30 minutes of laying the first pieces, especially in warm or dry conditions.
For the first week to ten days, keep the soil consistently moist through frequent, light watering, often two to four times daily, to facilitate root development. After the initial establishment phase, reduce the frequency, transitioning to deeper, less frequent watering to encourage roots to grow further down. Avoid heavy foot traffic for the first couple of weeks to allow the roots to anchor without disruption. The first mowing should occur about 14 days after installation, and the next fertilizer application should wait until the sod is fully established, usually four to six weeks later.