Why should you not treat couch grass with weedkiller?

It is a waste of time and money to treat couch grass with a contact weedkiller as it will not kill the underground stolons, which will just pop up elsewhere.

You need to use a translocating herbicide such as Roundup to kill from the roots up. This will of course take longer but is worth the wait. It is also important to apply it when the couch grass is growing strongly.

It will also kill any other plant it is applied to so be careful.