Weeds are opportunistic, unwanted lawn plants that exploit unhealthy, sparsely growing lawn environments. Michigan lawn weeds come in two basic varieties: grassy weeds which resemble lawn grass, and broadleaf weeds which have a broader, thicker leaf structure. Weed prevention and removal methods include pre- and post-emergent herbicides, mowing and physical removal.
Annual Bluegrass (Poa annua) is a grassy weed that grows in dense clumps. Apply pre-emergent herbicides during the spring and fall to prevent Annual Bluegrass germination in the early spring and late summer. Pre-emergent herbicides prevent weeds from establishing in the lawn.
Crabgrass (Digitaria sanguinalis) is a clumping, grassy weed with light green, coarse blades extending outward from a central node. Apply pre-emergent herbicides for four consecutive days in the early spring when the soil temperature reaches 55 degrees F.
Yellow Foxtail (Setaria glauca) is an erect, clumping, grassy weed that germinates in mid-spring when the soil temperature reaches 65 degrees F. Do not fertilize, aerate or over-seed the lawn when Yellow Foxtail is germinating, as this may induce weed growth.
Mouseear Chickweed (Cerastium vulgatum) is a low-growing, perennial, broadleaf weed that is found on lawns with a low cut height. Mouseear leaves are dark green, thick and hairy.
Common Milkweed (Asclepias syriaca) is a perennial, broadleaf weed with leaves extending laterally from a single vertical shoot. Prevent the appearance of this weed with routine mowing. Milkweed is found on unmaintained lawn areas and prefers direct sunlight and well-drained soils.
Prostrate Knotweed (Polygonum aviculare) is a summer annual, broadleaf weed that has green leaves extending from a dense network of multiple stems. Hand-pulling and post-emergent herbicides (herbicides that kill weeds after they have germinated) are the most effective method of removal.