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YARD AND GARDEN

Building tough turf Dave Robson

September is the ideal month to concentrate your energies on lawn care. Most lawns are composed of cool season grasses such as bluegrass, fescue and ryegrass. These plants thrive when temperatures are between 40 and 80 degrees Fahrenheit. Temperatures in the 90s and above tend to limit root and shoot growth.

The following are some of the activities that should take place in September.
Aeration is the process of pulling cores of soil out of the lawn. This allows the surrounding soil to collapse in the hole, ultimately loosening the soil. A loose soil allows for increased root growth which corresponds to a denser turf.

Aeration should take place when the ground is moist but not soggy. A core aerifier will not penetrate a hard soil. If the soil is too wet, the aerifier's spoons will keep spinning. Aerifiers that just punch holes in the ground can worsen a problem. The whole point of aerifying is loosening the soil; punching holes without pulling out plugs does nothing more than compact the soil around the hole. The hole won't collapse and root growth can be restricted further. The same thing applies to "shoes with nails" that you wear and walk across the lawn.

Lawns should be aerified once a year for maximum benefit. If you have a heavy clay or compacted soil, consider aerifying next spring.

Once the lawn is aerified, you'll be left with soil plugs on top of the lawn; it will look like a pack of dogs visited your yard. Allow the plugs to dry for a day and then mow. The plugs should disintegrate and topdress the grass plants.

As an added benefit, the layer of soil added to the top of the lawn can decrease thatch. Which brings us to the next chore.

Dethatching removes excess thatch that limits water penetration, increases diseases, ties up nutrients and allow turf to dry out quickly.

Before dethatching with a power rake or vertical mower, remember that some thatch is beneficial. Ideally, lawns should have a half inch of thatch. Layers greater than an inch thick will need removing. The only way to determine excess is to cut a core sample out of the lawn and measure the thatch layer present between the top of the soil and the grass blades.

Like aerification, dethatching should occur when the soil is moist.

Thatch removed should be raked off and composted. The grass roots and stems that make up thatch (grass leaves break down to quickly to contribute to thatch) won't break down fast enough on top of the lawn.

Fertilizing is important to stimulate new grass growth. In the fall, new shoot growth is more important than stimulating roots. One pound of actual nitrogen per 1,000 square feet is recommended. A formulation such as 33-0-0 applied at the rate of 3 pounds per 1,000 square feet, and watered in, will stimulate the turf to produce new plants. Make sure you apply the water regularly to avoid burning the grass with the fertiliser.

IMPORTANT: Plan on applying a winterizer fertilizer in November. This slow-release fertilizer feeds the lawn throughout the winter and early spring.

Keep mowing the gross regularly. Don't change the cutting- height. Maintain the turf at 2 inches for most lawns. This means mowing when the grass gets 3 inches tall. Clippings don't need to be collected if you only cut leaves and not stems.

Lawns can be improved by overseeding every two or three years. Adding new seed keeps diseases in check and improves the vigor of the turf.

It's important that the seed comes in contact with the soil in order to germinate. Slit seeders perform dethatching at the same time they drop seeds in the soil. If your thatch layer is satisfactory, rake the grass thoroughly after seeding to scratch the seeds into the surface.

In order for seed to germinate properly, the soil layer where the seed is located needs to be kept moist. It may be necessary to water the soil daily until the seeds germinate and are mown.

Fall gives better weed control of perennial broadleaf weeds such as dandelions and plantain. Chemicals selectively applied to just the weeds are translocated throughout the roots at the same time the plant is trying to store food for the winter.

Controlling the weeds at the same time the lawn is thickening means fewer weed problems next spring. Make sure to read and follow all directions on the label when applying any pesticide.

If you need to undertake several lawn practices, wait a day or two between each one so the turf plants have time to recover.

David Robson is an Extension Educator, Horticulture, at the Springfield Extension Center, Cooperative Extension Service, University of Illinois. You can write to Robson in care of Illinois Country Living, P.O. Box 3787, Springfield, IL 62708. Telephone: 217-782-6515. E-Mail: robsond@idea.ag.uiuc.edu

16 SEPTEMBER 1996 • ILLINOIS COUNTRY LIVING