Weeds and Your Lawn
Identify which weed species are present before selecting a management strategy. Most weeds are not problematic, while others can be invasive. Your best strategy to prevent a weed invasion is to maintain a healthy lawn.
Prostrate knotweed-a summer annual weed that trails along the ground with branching stems and small leaves. Reproduces by seed, and is one of the first summer annuals to emerge. Plants form a tough, wiry mat in areas of low fertility and in compacted or other stressed sites.
Slender speedwell-a creeping perennial weed with attractive blue flowers in the spring and small round leaves with scalloped margins. Reproduces in New York primarily by underground stems. Plants remain green year-round.
In areas where the turf is thing, overseeding (planting new seed on an existing lawn) will help grasses out-compete weeds. Prepare the area to be seeded with close mowing or aerification to expose or loosen soil, and ensure that seeds and soil make contact. Irrigate to aid early development. Consider fertilizing once grasses are established.
Remove sources of weed seeds. Many weed problems occur as a result of seeds drifting from adjacent sties as well as from weeds already present in the lawn. Thistle and millet seed bird feeders are a frequent source of these weeds.
Many weeds can be controlled with herbicides during early development, while some are more easily pulled by hand. Many hand tools exist for removing specific weeds.
Susceptibility to herbicides varies considerably and most weeds are better managed by spring and fall applications. Check the Cornell Guidelines for management strategies or the names of herbicides that will be effective for the weed species present at your site. Time, money, and product will be wasted if herbicides are used improperly.