The Homeowners Column

The Homeowners Column

Time to seed lawns

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

By August the spring surge and urge to work in the lawn has dwindled to a faint spark. However in central Illinois August 15 to September 15 is an ideal time to seed lawns with our cool season grasses of Kentucky bluegrass, perennial ryegrass, fine fescues or tall fescue. In contrast to spring seedings, fall seedings have less weed competition, good temperatures and moisture for quick growth and time to develop a good root system before summer's heat.

Don't be tempted to cut corners when preparing the soil before seeding. Even though grass plants are small they still need proper soil conditions for long term success. Plus correcting problems after the turf is established is tough.

Here are the preparation steps for seeding or sodding:

  1. Control weeds. Eliminating weeds, especially perennial grassy weeds such as quackgrass is much easier before planting. Tilling seldom kills perennial weeds. Non-selective herbicides such as glyphosate may be used at this time. Wait to seed until weeds are dead in case reapplication is needed. There is no soil residual that will effect the seed establishment. Read and follow all label directions.
  2. Rough grade site to facilitate surface drainage and remove debris. Generally, a 1 to 2 percent slope (a drop of 1 or 2 feet for every 100 feet of run) away from buildings is adequate. Remove all debris brought to the surface.
  3. If topsoil is needed, incorporate it into the existing soil during rough grading. The final depth of topsoil should be at least two inches.
  4. Get soil tested. Soil testing provides valuable information to determine how well soils can support turf. For a small fee, commercial testing laboratories will evaluate soil pH and some nutrient levels.
  5. Amend soil as necessary. Turfgrass does best with slightly acidic pH (6 to 7). Add sulfur to lower pH or limestone to raise pH and any fertilizers as recommended by the soil test. Generally 10 pounds of 10-10-10 fertilizer (or its equivalent) per 1,000 square feet supplies minimal fertility. Amend heavy, clay soils with generous amounts of organic matter to improve the soil's drainage, aeration and nutrient holding capacity. If possible, apply a two inch layer of compost or some other quality organic material to soil. Check out the Landscape Recycling Center 1210 East University in Urbana, IL PH: 217-344-5323 for compost.
  6. With a rototiller work amendments into the soil to a depth of 6 to 8 inches.
  7. Fine grade the site. After rototilling soil particles should be marble sized or smaller. Fine grade the site until it is smooth. Eliminate depressions. Now the site is ready for seeding or sodding.

After site is prepared:

  1. Select proper seed for site. Use mixes of different grasses.
  2. Seed at appropriate rate for seed type.
  3. Provide good seed-to-soil contact by raking and light rolling.
  4. Mulch with a thin layer of clean straw. Soil should be visible beneath straw. Do not remove straw after seed germinates.
  5. Provide adequate water. Keep top ½ inch moist. Germination duration - Kentucky bluegrass 10-30 days; perennial ryegrass 3-10 days and tall fescue and fine fescue 7-14 days.
  6. Once seedlings have emerged irrigate less frequently but more thoroughly.
  7. When seedlings reach two inches tall, fertilizer may be applied at a rate of 1/2 pound of actual nitrogen per 1,000 square feet (if applying 10-10-10, use 5 pounds per 1,000 square feet).
  8. Maintain mowing heights at 2-3 inches. Never remove more than one-third of the grass blades at any mowing.
  9. Limit heavy traffic during the first growing season.

Late summer is also a good time to overseed (adding seed to an existing lawn) to thicken the lawn or fill in bare areas.

For more information http://urbanext.illinois.edu/lawntalk/

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