I use Treflan granules for pre-emergent weed control on some of my garden and flowerbeds. It does not kill anything after it has come up just as it germinates. Safe for most of garden , but not all such as corn, onions , strawberries etc.
Preen is one of the name brands but I don't know if it has the veggies on the label for use. Google trifluran and you can see a lot of the products and info. I get it the at local Co-op.
I used to use Dacthal some years ago. It is also pre-emergent applied and labeled for some of the other crops.
Both of these are older herbicides. I don't know if you could even find the Dacthal now.