How can I prevent weeds from coming up and competing with new grass in my lawn?

To prevent weeds from competing with new grass in your lawn, you can apply a pre-emergent herbicide in the spring to stop weed seeds from germinating. Additionally, maintaining a healthy lawn by regularly mowing, watering, and fertilizing can help prevent weeds from taking over. Hand-pulling weeds as soon as you see them can also help keep them in check.