However, if that old pasture has a considerable amount of Kentucky bluegrass, other undesirable grasses, and weeds, it is far better to use a herbicide such as Roundup® to kill the existing vegetation prior to the no-till seeding of the cool-season mix.

In the case of a spring seeding, one would want to wait until about April 10 to 15 to have many of the undesirable grasses actively growing, apply the herbicide, and then in several days, seed the new grass mix.

When a herbicide is not used, existing vegetation can be very competitive with the new grass seedlings and, oftentimes, only a relatively small amount of the new grasses will become established.