The best time to apply 2, 4-D weed killer on your lawn is when weeds are still young and starting to grow. This may be during spring, although some weeds germinate in fall and summer. Spray 2,4-D at least 6 weeks after newly seeding or sodding your lawns to prevent retarding the grass.

How long after seeding can I use 2,4-D?

Answer: You did not mention which 2,4-D product you wanted to use but most product labels give instructions that state you must wait 3 weeks after seeding or a second mowing has been done. 75 of 86 people found this answer helpful.

Does too much 2,4-D kill grass?

2,4-D is a powerful post-emergent herbicide. Although it is designed to attack broadleaf plants (weeds, garden plants, trees, shrubs) and leave grass unharmed, if it is applied too heavily it can harm your grass. Signs of overapplication of 2,4-D include: Brown or dead grass.