Seeding and Sodding Lawns
Site Preparation
Whether seeding or sodding, home lawn quality is closely tied into how well the soil and site were prepared prior to lawn establishment. Taking shortcuts often comes back to haunt the homeowner in the form of chronic lawn problems, such as thatch, weeds, and disease.
Lack of topsoil, soil compaction, and construction debris makes this soil
unsuitable for lawns unless modifications take place.
Eliminating weed problems existing on the site is an important first step. Perennial weeds, such as quackgrass, need to be controlled prior to seeding or sodding the lawn. One option is to dig them out by hand, making sure roots and stems are completely removed. Another option is to use 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 seedlings. Read, understand, and follow all label directions.
Another important step in preparing for lawn establishment is to thoroughly work the soil (by rotary tiller) before seeding or sodding. 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.
The lawn on the left is declining due to poor soil preparation; the lawn
on the right is doing well because the soil was prepared properly.
Soil testing is also suggested prior to establishment. Check with your local Cooperative Extension Office on how to get a soil test. 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 and lawns will get off to a better start when soils are modified prior to establishment. Lawn grasses prefer soil pH values between 6.0 and 7.0 (slightly acidic).
Lower soil pH (make more acidic) by adding elemental sulfur. Raise soil pH (make more alkaline) by adding limestone. Only add these materials when soil tests indicate a need and base the rate on soil test results. 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 nutrient shortages which would influence 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 rocks or other debris. Avoid burying any construction debris, as this could cause problems for the grass later. Eliminate any depressions or raised areas. Final slopes should be one to two percent away from buildings (one to two feet drop per 100 feet of run) to assure good surface drainage.
