Extension Educator, Horticulture
It's time for our yearly discussion about sowing grass seed. For most people the spring surge and urge to work in the lawn has dwindled to a faint spark by now.
However in central Illinois August 15 to September 15 is an ideal time to seed lawns with Kentucky bluegrass, perennial ryegrass, fine fescues or tall fescue. In contrast to spring seedings, fall seedings have less weed competition, good temperatures 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 much more difficult.
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. Don't assume tilling will kill perennial weeds. Non-selective herbicides such as glyphosate sold as Roundup may be used at this time. Wait 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.
If topsoil is needed, incorporate it into the existing soil during rough grading. The final depth of topsoil should be at least two inches.
3. 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.
4. Amend soil as necessary. Turfgrass does best with slightly acidic pH (6 to 7). Add sulfur or limestone to change pH and any fertilizers as recommended by the soil test. In the absence of a soil test, use 10 pounds of 10-10-10 fertilizer (or its equivalent) per 1,000 square feet to supply 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 sphagnum peat moss, manure, compost or some other quality organic material to soil. Check out the Landscape Recycling Center PH: 217-344-5323 in Urbana for compost.
5. With a rototiller work amendments into the soil to a depth of 6 to 8 inches.
6. 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.
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. Should see soil 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.
For more information, visit http://www.urbanext.uiuc.edu/hort/.