We put down newspaper in the rows to keep back the weeds. The boys enjoyed laying them all out, and the soaking them with the hose. We also laid a few rocks out to make sure the newspapers did not all blow away. Now we can concentrate on weeding the tops of the rows, instead of the places where we walk.
Now, the boys spend most of the time climbing the big tree, waiting for the plants to grow, and Mom does the weeding. At this point, I don't mind, because I don't want them to accidentally pull out one of the vegetables.