Two types of lawn weeds generally grow in northern Illinois: those that grow in the cool season and the warm season. Because weeds grow almost all year long, northern Illinois gardeners should apply pre-emergent herbicide to their lawns and gardens in the spring and fall months. In addition, identify the weeds growing on your landscape. Most herbicides are chemically formulated to kill common Northern Illinois weeds such as a grassy weed, broadleaf, or sedge.
Things You'll Need
- Soil pH testing kit
- Bypass shears
Walk around your lawn or garden to find weeds. There are three common types of weeds that differ in appearance. Broadleaf weeds typically grow flowers, and are more colorful than grass. Grassy weeds have a round hollow stem with a prominent mid-vein. Sedges have triangular stems. The majority of Northern Illinois gardeners will have problems with at least one of these weeds in their yards at any given point. The University of Illinois sites dandelions, crabgrass, and yellow nutsedge as examples of all three weed types that commonly invade Northern Illinois yards.
Look among your yard to find grass invading your turf. Any intruding grass is considered a weed. Tall fescue and bentgrass are common grassy weeds which spout in Kentucky bluegrass in Northern Illinois, according to the University of Illinois. Tall fescue can grow up to 4 feet and has green basal leaves. Bentgrass grows low to the ground and has slender leaves. Other common grassy weeds include quack grass and nimblewill.
Dig up the weed to look at its root system. Perennial broadleaf weeds have a longer and more extensive root system than annual broadleaf weeds. Annual weeds have a small tap root with smaller roots growing off. Press a shovel into the ground next to the weed and push the weed up from underneath in order to avoid disturbing its root system. Lift the weed up from the ground and measure the length of the root system. Weeds such as field bindweed can grow up to 20 feet deep.
Conduct a soil pH test on the area. All vegetation must have a specific pH range in order to absorb the soil's nutrients. By knowing what your soil's pH is, you can narrow down the list of possible weeds in the yard. For example, bentgrass needs a pH range between 5.0 to 7.0, while dandelions need a range between 4.8 to 7.5. Purchase a soil testing kit from your local cooperative extension office. Dig a six-inch hole and collect half a quart of soil to mail or drop off. Wait for the results and use them to identify types of grassy weeds or broadleaf weeds that may be growing in the yard.