Laying fresh sod requires a clean slate to ensure the grass establishes a robust root system. Existing turf and weeds act as a physical barrier, preventing the new sod roots from making direct contact with the underlying soil. Competition for water and nutrients, combined with the risk of an uneven surface from decomposing material, makes complete removal of the old grass necessary for a healthy, long-lasting lawn.
Chemical Removal Methods
One efficient way to clear an area is by using a non-selective herbicide that kills all vegetation it contacts. Products containing the active ingredient glyphosate are commonly recommended because they are systemic, meaning the chemical is absorbed through the leaves and travels down to kill the root structure. This deep kill is effective against stubborn perennial grasses and weeds.
Always follow the manufacturer’s directions, paying close attention to the mixing ratio and application conditions. The herbicide should be applied on a calm day when rain is not expected for at least 24 hours, allowing the chemical time to penetrate the plant tissue. For optimal results, water the area a week before application to encourage active growth, which helps the plants absorb the herbicide more effectively.
After the initial application, a waiting period is required to ensure the herbicide has fully translocated and the vegetation is dead. This period is typically between seven and fourteen days; sometimes a second application is needed for tough weeds like St. Augustine grass. Although glyphosate becomes inactive once it contacts the soil, waiting this duration ensures the death of the existing grass and allows for the removal of all dead organic matter before the new sod is laid. Ensure all pets and children are kept away from the treated area until the spray has completely dried.
Mechanical Removal Techniques
Mechanical removal offers a faster solution, allowing for immediate sod installation without chemical delay. The most effective tool is a sod cutter, a specialized machine available for rent that slices beneath the turf. A sod cutter is adjusted to cut through the turf and a thin layer of soil (usually one to two inches deep), lifting the old grass in neat, manageable strips.
The strips are then rolled or folded up and removed from the site, providing a clean surface ready for preparation. This method is favored because it removes the entire root system, eliminating the risk of regrowth. For very large areas, a wheeled sod cutter is faster and less labor-intensive than manual digging.
Another option is using a rototiller, which uses rotating blades to chop up the existing grass, roots, and soil. Tilling breaks up compacted earth and mixes organic material into the topsoil. However, tilling risks bringing dormant weed seeds to the surface, where they can germinate and compete with the new sod. If a rototiller is used, rake out and remove all visible grass clumps and debris thoroughly, rather than simply tilling the old turf back into the soil.
Passive and Organic Grass Removal
For those who prefer a non-chemical approach and are not in a hurry, passive methods like solarization provide an alternative. Solarization involves covering the mowed lawn with clear plastic, creating a greenhouse effect. This process traps solar heat, raising the soil temperature high enough to kill the existing grass, weeds, and even some soilborne pathogens.
This method is most effective during the hottest part of the year and requires a significant time commitment, typically needing four to eight weeks for elimination. Another organic method is sheet mulching (smothering), using layers of biodegradable materials like unwaxed cardboard and compost. This technique blocks sunlight, causing the grass to die and decompose naturally while simultaneously enriching the soil. While sheet mulching is excellent for soil health, it is a slow process, making it less practical when sod installation is planned for the immediate future.
Final Site Preparation Before Laying Sod
Once the existing grass is removed, the area must be cleared of dead material, rocks, sticks, and large clumps of soil. Thorough debris removal is important because organic matter left behind will decompose and create an uneven, lumpy surface under the new sod. The exposed soil should then be tilled to a depth of at least two to three inches to loosen compaction and promote root penetration for the new turf.
The next step involves grading and leveling the area to ensure proper drainage. The soil surface should slope gently away from all structures, and a long, straight object can be used to smooth the surface and eliminate high and low spots. The final grade should rest approximately three-quarters of an inch to one inch below hard edges (like sidewalks or driveways) so the new sod will sit flush.
Soil amendments should be incorporated, with compost or screened topsoil tilled into the prepared earth to improve soil structure and nutrient content. A starter fertilizer, typically higher in phosphorus to encourage root growth, can be raked into the top layer of soil. Finally, the prepared soil should be lightly moistened immediately before the sod is laid; a moist base prevents the soil from drawing moisture out of the sod and encourages rapid root attachment.