Preen is what you are looking for. It is the lawn and garden name for agricultural Prowl. At least it always used to be.
You can probably find it already mixed into dry fertilizer or mixed into a dry kitty litter type stuff.
This is not meant to be a substitute for reading the label Okay? It will kill anything germinating from a small seed, think mustard seed size. Mainly this includes grasses, pigweed, and lambsquarter. Not that effective against cockleburr and no use whatsoever against perenial weeds like thistle or dandilions, or lawn grasses. The chemical is absorbed through the roots only. This means if it is too deep >2" It will be less effective, if it is too shallow <.5" same problem. Now comes the beauty part of Prowl... It will move a bit in the soil with the rain water! The same rain water that makes the weeds germinate.
Here is what this is all leading up to. Veggies that have a big seed, corn, polebeans, turnips, and set plants like tomatoes, cabbage, green peppers and the like will likely grow right thruogh the Preen. Small stuff, lettuce, radishes, carrots, and the like will not make it probably.
Here is my suggestion, till your garden, level it and plant it all within a week or so. This is actually important because the day you till starts the emergence clock on weeds, you reset the clock to some extent at every tillage. Within a week spray or so spread the recommended amount of chemical over the garden. Now water the garden or have rain fall equal to 1or 2 inches. This is what is going to wash the chemical off of the granules and mix the chemical into the soil to the level the weeds are germinating at. If you find weeds are escaping lightly hoe the garden keeping in mind that as you uncover untreated soil ie. deeper soil it, will bring up weed seeds that may well root into untreated soil.
What I've recommended may not be exactly legal but it does work. I spent 4 years of college and 10 yrs in the ag industry so I do know a bit about the subject.
(I used Lasso most of the time but it's pretty hard to come by for the normal person).