Likewise, should I overseed or kill weeds first? You apply pre-emergent herbicides before weed seeds germinate, typically in the spring. You can apply them before you sow your grass seed. If you apply a pre-emergent herbicide that kills weedy grasses, you have to delay sowing your lawn seed.
Why do I have weeds in my new lawn?
This waiting time is true of most broadleaf herbicides. Once again, read the label. In addition to the waiting time after germination, there is also a wait time for herbicide application before seeding. Chemicals applied four to six weeks before seeding can also have an adverse affect on the tender young grass.
Furthermore, how do you kill weeds in newly seeded grass?
Similarly, how soon after planting grass seed can you spray for weeds?
Can I spray weed killer on recently seeded lawn? I don’t want the weeds to take over before my new lawn gets established.
Lawns seeded in spring tend to get weedy, which is one reason why autumn is the recommended time for planting cool-season grasses (such as Kentucky bluegrass and tall fescue). Before applying an herbicide, wait until new turf grows enough that it requires mowing three times. Young grass plants are sensitive to weed killers and may be damaged if the herbicide is sprayed too soon.