Soil and Site Preparation for Lawns

Success or failure of a home lawn is closely tied into how well the soil and site was prepared prior to lawn establishment. Eliminating weed problems existing on the site is an important first step. Perennial weeds, such as quackgrass, need to be controlled prior to lawn seeding or sodding. Weed control options include digging by hand or using a translocated (moves within plant) nonselective herbicide, such as glyphosate, sold as Roundup and other trade names. Glufosinate ammonium (Finale) does not translocate, so may only provide limited control of perennial weeds. Both herbicides don't leave active soil residues that would harm lawn seedlings. Read, understand, and follow all label directions.

Before seeding or sodding, it's very important to thoroughly work the soil (by rotary tiller). Amend poor soils, such as heavy clay, by adding organic matter. Sources include compost, rotted manure, peat, and quality topsoil. Incorporate these materials into the existing soil, rather than layering them on the surface. Sand is not suggested as a material to improve clay soils for home lawns. Six inches or more of well prepared soil is suggested.

Soil testing is also suggested prior to establishment. Key information revealed by soil testing includes soil pH and amount of available nutrients such as phosphorus (P) and potassium (K). If major modifications are needed, it is easier to make these prior to establishing the lawn. In addition, the lawn will get off to a better start when soils are modified prior to establishment. Check with your local Cooperative Extension Office for details on how to get a soil test.

Starter fertilizers may also be mixed into the soil surface prior to lawn establishment. Starter fertilizers typically have balanced ratios of nitrogen, phosphorus, and potassium (N, P, K), such as 10-10-10 or 12-12-12. Soil test results may reveal a shortage of phosphorus or potassium, which would influence the decision of how much starter fertilizer is needed.

When preparing the soil, it's important to establish a favorable final grade. Rough grading should include removal of any rock or other debris. Avoid burying construction debris, as this could cause problems for the grass later. Eliminate any depressions or raised areas. Final slopes should be 1 to 2 percent away from buildings (1 to 2 feet drop per 100 feet of run) to assure good surface drainage.

Taking shortcuts in soil and site preparation often leads to assorted lawn problems later. Take the time and effort to do a thorough job before seeding or sodding.