How to seed a new lawn in a previously extremely weedy area! - Ask Extension
Hello!
I recently had half of my backyard cleared after it was overcome with shrub trees and many many weeds. I hired someone to clear the lot and br...
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How to seed a new lawn in a previously extremely weedy area! #927838
Asked April 08, 2026, 2:45 PM EDT
Hello!
I recently had half of my backyard cleared after it was overcome with shrub trees and many many weeds. I hired someone to clear the lot and bring it about 2-3 inches of new top soil. I want to start a new lawn back there by seed; however, I can already see the weeds starting to grow. How can I safely use an herbicide to kill the weeds and weed seeds before I plant my new grass seed? What herbicide would I use? what is the timing?
Ramsey County Minnesota
Expert Response
A broadleaf herbicide will take care of the weeds. However, it will not kill grassy weeds. Crabgrass preventers will not allow seeds to sprout but those already growing and perennial will continue to grow. You are probably going to have to use a non-selective herbicide (like Round Up} and kill everything. Follow the directions exactly. Also make sure you purchase the right formula. There are some which will not allow for any plants to grow for up to a year! Those are meant for cracks in driveways, etc. Once the prescribed amount of time has passed, you will be able to start planting. I am giving you a link: https://extension.umn.edu/lawn-care/renovating-lawn-quality-and-sustainability
