University of Illinois Extension


Bruce Spangenberg,
Extension Educator, Horticulture
Rockford Extension Center

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Ideal Time for Lawn Renovation

Early fall is an ideal time for renovating lawns in northern Illinois. Renovation can involve a variety of lawn care practices, depending largely on the condition of the lawn and underlying soil conditions. Many lawn problems originate from poor soil conditions, such as heavy clay, compaction, and poor drainage. These situations should be corrected during renovation.

On the other hand, many lawn problems tend to be due to pests, weather conditions, or poor lawn care practices. Sometimes simply improved mowing, fertilizing, and watering may be all that's required to achieve acceptable lawn quality.

The lawn renovation process can be much easier if the proper equipment is used. For example, core aerification is often suggested for lawn care, especially for sodded lawns sitting on clay. This process is very useful to help reduce soil compaction and thatch, improve surface drainage, and improve conditions prior to overseeding. Core aerifiers insert hollow tines into the lawn and pull out plugs of soil. Size of cores removed will depend on the machine used, soil moisture, and type of soil. Core spacing also varies with the specific machine being used. Machines can be rented or aerifying services are available for hire.

Vertical mowers are machines with rotating blades arranged vertically that can cut into turf and soil. These machines can be used to remove thatch, and are sometimes called dethatchers. Turfgrass rooting in the thatch is typically torn out, so reseeding is suggested afterwards. Vertical mowers can also roughen the soil prior to overseeding areas.

Another very useful machine for renovation procedures is the slit-seeder, which combines vertical mowing with seeding. As the machine goes across the lawn, it opens the soil and deposits seed directly into the soil opening. Most slit-seeders have a roller that helps firm the soil after seeding. Seed is metered at a predetermined rate; it's suggested to apply half the desired seeding rate in one direction and the other half on a second pass perpendicular to the first.

Since the seed is placed in direct contact with the soil, seeding success is usually high when using slit-seeders. In addition, existing grass and debris does not need to be completely removed prior to the overseeding process. Timing should be the same as for conventional lawn seeding, which ideally would be late August into early September. Many rental agencies carry slit-seeders or many lawn and landscape services can do it for hire.

Once the problem has been identified, the renovation process may begin. Renovation may be as simple as correcting basic care practices. It may also just involve overseeding with little additional work. Another option is allowing existing grass to remain but working on reducing thatch and overseeding. The final option is completely removing the existing lawn and starting over, which may be required for poor lawns sitting on very poor soil conditions.

Base the decision of which option to choose on how much desirable grass exists and the soil conditions. For example, if the lawn is just a little thin, overseeding with a quality lawn seed in late August or early September may be the answer. Use of a slit-seeder is an ideal way to overseed lawns. Seed may also be broadcast over thin lawn areas, but there needs to be good soil to seed contact. Dethatchers or vertical mowers can also be used to tear out excess debris prior to overseeding. In addition, slit-seeding could also be done directly through grass and/or weeds killed with the nonselective herbicide glyphosate. All of these types of overseeding procedures do not require additional soil modification.

When soil problems exist under a lawn, there are ways to address them without tearing up the lawn. As mentioned earlier, core aerifying is suggested for problems such as thatch and soil compaction. Aerifying and then overseeding or slit-seeding (breaks up cores) may be an ideal level of renovation for many lawns.

Unfortunately, some lawn problems, such as soil problems of severe compaction, high clay levels, or poor drainage, may require starting over. Remove existing grass or rototil it. High populations of perennial weed species may require use of a nonselective herbicide, such as glyphosate. Thoroughly work the soil to a depth of 6 inches. Add amendments such as compost, rotted manure, organic topsoil, peat, etc. Follow proper selection and establishment procedures to get the new lawn off to a good start.

August - September 2000: Gypsy Moth: Know the Facts | Flood Tolerant Trees | Saving Seed from the Garden | Ideal Time for Lawn Renovation

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