Guide to Preparing a Lawn for Grass Seed

Clearing the Bed

• Removal of weeds, old turf and any debris creates a clean seed bed that is prone to less problems later on. Digging and removal of the weeds manually takes time, effort and does not remove any seeds in the soil. Treating the bed with a glyphosate non-selective herbicide kills all plants and weeds in the bed but only remains active for a short time, leaving behind no harmful chemicals that damage the grass seed. Removal of the dead plant material is still necessary after an herbicide treatment.

Soil Testing

• Lawn grass requires a soil pH between 6.0 and 7.0 to grow well. A soil test performed prior to seeding indicates the pH level of the soil and also determines the amount of phosphorus and potassium in the bed. Tests are available from extension offices and garden centers. Extension office tests are more in-depth than kits sold by most garden stores. The results are determined at a lab and may be more accurate. A test also indicates any necessary amendments and their amounts for improving the seed bed.

Amendments

• Most seed beds require a lime or sulfur amendment to adjust the pH of the planting site prior to sowing the lawn grass seed. Limestone raises the pH of the soil and sulfur lowers it. Most beds also require a starter fertilizer application. These supplement the nutrients found naturally in the soil and make up for any nutrient deficiencies determined by the soil test. Balanced, general-purpose fertilizers are typically used for starter fertilizer applications, with the amount used based upon the test results. Compost or peat moss amendments are also used to improve the soil texture in heavy clay or sandy sites.

Grading

• The amendments are tilled into the top 6 to 8 inches of the seed bed so they become available to the grass roots once the seed germinates. Grading occurs after the amendment additions, smoothing the seed bed and providing an even slope. Lawns require grading at a slope away from the home or building so irrigation water won't pool around the foundation of any structure. Rocks and any remaining debris are removed during the grading process, leaving behind a smooth seed bed that is ready for sowing.