Posing a hazard to many landscapes and lawns, crabgrass displays the aggressive tendencies found in many other types of weeds. Left unchecked in a new lawn, crabgrass often chokes out the more desirable varieties of grass. New grass seed is especially susceptible to damage from crabgrass due to its fragile, immature root systems. A healthy lawn relies on early removal of crabgrass. Eliminate this unsightly grass by creating a dense carpet of desirable grass from the start.
Remove existing crabgrass from your planting site before laying new grass seed by lightly tilling the soil to uproot existing crabgrass. Run a garden tiller over the surface before crabgrass goes to seed. Rake out loosened roots and runners with a good garden rake. Remove every trace of vegetation from your planting site. Go over the area with the tiller again to break up dirt clods.
Apply a pre-emergent herbicide to kill crabgrass seeds before they germinate. Select an herbicide formulated to kill crabgrass while not harming other types of lawn seed. Follow all instructions on the herbicide container regarding application procedures, including the correct waiting time, before planting your new grass seed.
Check for sprouting crabgrass as your planted seeds begin emerging from the soil. Gently pull up any obvious clumps of crabgrass as you notice them in your new yard. Apply a post-emergent herbicide for crabgrass after your new grass seed sprouts. Again, select a formulation specifically intended for use on your variety of lawn grass to avoid damaging desirable grass seeds and new seedlings. Follow all package instructions when applying the herbicide to your new lawn.