Healthy lawns will choke out the persistent crabgrass plant. The warm weather annual grass is easily propagated through small seeds. These seeds will readily germinate in any open areas of a lawn. Overseeding the lawn with the current species of planted grass will aid in depriving sunlight from the crabgrass seeds. Maintaining a healthy lawn through proper fertilization, watering and mowing will also go a long way in keeping a vigorous growing lawn. Lawns with a high level of health are generally able to keep any errant weeds in check.
Catch and collect all grass clippings from the late fall mowing. Dispose of these clippings in either a compost pile or to the city mulching service. Collecting the grass clippings will go a long way in capturing seeds from any crabgrass plants that would germinate the following spring.
Attach a thatching blade to the lawn mower. Thatch is the dead grass material and other debris that will collect on the soil surface just below the grass. Removal of the thatch material will create more bare soil exposure for the new grass seed when applied to the lawn.
Run the thatching mower in a single direction across the lawn--for example, in a north south direction only. Rake the material from the lawn with the leaf rake. Dispose of the thatch material onto a compost pile or to the local composting program. The fully decomposed thatch can be added back onto the lawn in late fall as an organic material.
Seed the thatched lawn with the specified amount according to grass species and any nursery recommendations. Various species of grasses and local growing conditions will dictate the amounts of grass seed applied to the lawn.
Broadcast lawn fertilizer onto the lawn before watering. A general-purpose lawn fertilizer maybe ideal. Consult your local agricultural extension service if you desire to conduct a soil test of the lawn area. Soil tests will give specific recommendations for fertilizers and application rates.
Apply a pre-emergent herbicide as a last resort if the grass lawn is too heavily infested with the weed. Follow label directions for applications. Re-seeding the lawn will have to take place after the herbicide has affected the crabgrass seed. The herbicide may also kill certain grass species seedlings as well.