When to Apply Weed Killer and Reseed

• Timing is important for weed killer applications and reseeding. Gardeners want to plan on reseeding their lawns when temperatures promote seed germination and growth. Typically, early fall is a good time to remove weeds and reseed the lawn, according to the University of Minnesota. It is important that you pick a time where there is some soil moisture. Furthermore, weed killers should be applied when there is a 48-hour window of dry weather so the herbicide can become absorbed into the foliage.
  
  

Applying Weed Killer

• Use a non-selective weed killer that contains glyphosate, as recommended by the University of Minnesota. Herbicides that contain glyphosate do not prevent grass seed germination or kill off emerging seedlings. Avoid mowing for two days before spraying your weed killer. The more surface area your weeds have the better the results. Spray your lawn or area with the weed killer. Wait two days before mowing the lawn again. Plan on seeding the sprayed areas in five to 14 days, as suggested by the University of Minnesota.
  
  

Site Preparation

• Regardless if you are reseeding a small area or entire lawn, soil must be prepared for grass seed germination. Break up the first 4 to 6 inches of top soil to encourage grass seedling root development. Apply a starter fertilizer that has a NPK amount of 5-10-5 over the area. Distribute at a rate of 20 lbs. per 1,000 square feet. Work the starter fertilizer into the first 6 inches of soil. Water the area to moisten the soil right before seeding.
  
  

Reseeding

• The amount of grass seed you distribute over your lawn depends on the type of grass you are growing. For example, Bermuda grass seed must be distributed at a rate of 1 lb. per 1,000 square feet. Cover your grass seed with a 1/8 inch of compost to help lock in moisture. Keep the grass seed moist. Dry grass seed will not germinate. Water the seeded area for the first week once or twice a day. Reduce your watering schedule to once a week when seedlings grow to the height of the surrounding grass.