When Can I Overseed After Use of a Pre-emergent Herbicide?

One of the most frequently asked questions and sources of confusion we encounter surround the topic of seeding and use of crabgrass control. In the spring, many homeowners pick up crabgrass preventer and seed from the local home or garden center. When they return home, they apply those products to bare spots in their lawn and hope this fixes them. However, their hopes are dashed when the seed never comes up and the bare spots do not fill in properly.

Almost every pre-emergent herbicide, intended to prevent grassy weeds from germinating, also prevents grass seed from germinating. Do not apply pre-emergent herbicide if you have bare spots you plan on seeding into. Generally, once a pre-emergent herbicide is put down in the spring, you cannot effectively seed until fall. Technically, you could seed 16 weeks from the application, but that puts you in the hottest part of summer. Seeding is not advisable at that time.

If you find yourself with an overall poor stand of grass to begin with, where seeding would be helpful, you might skip the pre-emergent application completely. Seed the area and treat grassy weeds with a post-emergence herbicide as they come. Speak to your Advanced Turf Solutions representative for more information on what strategy you should use for your specific situation.