My neighbor tried to kill dandelions in his grass using a regular vinegar mixed with water and I believe dawn dish soap.
It took 3 years for the spots to go away in his yard.
I learned that preen only prevents seeds from sprouting. It has no effect on perennial weeds like bind weed and runner grass that come back from dormant roots.
I do a lot of pulling of weeds in spring while the ground is softer. Summer through fall I have been laying black plastic on top of...