A lawn infested with weeds often is a sign of a lack of proper care. According to Kansas State University, the best defense against weeds in the lawn is proper fertilization, watering and mowing. The use of herbicides in controlling weeds is only part of the overall health care for turf grass. Healthy turf grasses generally will choke out all unwanted plants, including weeds, from the lawn. When weeds begin to overtake the turf grass, reseeding the infested area is just one practice in controlling the unwanted plants.
Conduct a soil test of the lawn. Take soil samples from several locations where weeds are growing. Mix all of the soil samples together. Dry the soil thoroughly. Take the soil sample to your local agricultural extension service. The soil analysis will detail the deficiencies that are present in the lawn's soil.
Collect samples of the weed plants that are most present in the lawn. Take these plant samples to the extension agent when you deliver the soil sample. Knowing which weeds are present will allow the agent to aid you in creating a custom defense against them.
Attach the thatching blade to the lawn mower. Follow the manufacturer's directions in attachment and proper usage. Remove all thatch from the lawn. The thatch material is all dead grass and foreign debris that lie just under the green blades of grass, and on top of the soil.
Rake the thatch material from the lawn. Collect into piles. Move the piles into a main compost bed. The composted thatch will be added back to the lawn in the late fall of the year as a topsoil amendment. In some cases, if the soil is too compacted, the extension agent may suggest using a mechanical aerator to open up the soil. Mechanical aerators can be rented from local equipment rental facilities. All rental facilities offer free training and guides in the proper operation of the equipment.
Amend the soil based on the analysis results from the soil test. Broadcast the recommended amounts of fertilizer and agricultural lime to the lawn.
Irrigate the fertilizer and lime into the soil of the lawn. Follow the recommendations from the extension agent. In most cases, applying an inch of water to the lawn's surface will allow the chemicals to leach into the soil.
Seed the lawn with the same species of grass that exists in the turf. Use the labeling directions on the seed container for correct application rates. Generally, broadcasting ¾ of a pound of grass seed per 1,000 square feet will be sufficient.
Irrigate the freshly planted grass seed deeply. Allow the water to soak into the turf to a depth of 4 to 5 inches. Keep the seed moist. The seed will typically germinate in five to seven days.
Mow the new grass when its overall height reaches 2 to 3 inches. Follow the extension service's recommended watering and mowing schedule for your species of lawn grass.
Apply a plant herbicide, specific for the weed plant species, if all else fails. In some cases, the entire lawn may have to be killed with a full-range herbicide and then replanted in order to re-establish a full turf grass species.