How do I get rid of oregano and mint that have taken over what I wanted to be my herb garden?
Certified GKH Gardening Expert
You have many options here. The safest way to do this without making the soil toxic would be to pour boiling water on everything in there once per day until it is all dead. This will not take long, and can happen with the first application.
I always recommend planting invasive herbs in container. This will ensure that the plant cannot spread. It can be difficult to control once they get established.