• Grass should not be mown until after weed killer is applied.dandelion image by Igors Leonovs from Fotolia.com
  
  

Mowing Before

• Mowing a lawn before applying weed killer may make the weeds easier to spot, or you may have just noticed the weeds after mowing and wish to apply weed killer as soon as possible. Mowing before using weed killer can also expose much more of the plant, making it easier for weed killer to penetrate.
  
  

Mowing After

• Weed killers that come in granular form need something to land on in order to kill the weed, and in the case of most lawns weeds, that something is the leaves. If the leaf is chopped off of the plant when the lawn is mowed, then the granular pieces can't sit around long enough to kill anything. The larger the weed surface area, the more effective the weed killer will be, so the lawn should be mowed after weed killer is applied.
  
  

Bottom Line

• Lawns should not be mowed until at least five days after using weed killer in order for the weed killer to be able to stick to the leaves and have enough time to kill the entire plant.