Preen for my tomato patch?

[coloken]

Believe it or not, I had never heard of preen until now. It is in all the stores. Before i do my garden space for tomatoes with it I need some reasurance from others about it. My whole year depends on me not making a mistake to try something that is new to me. My biggest problem is what I call wild millet or a foxtail type of grass that comes up late in the year. Do I just spreed the preen all over before or after I put in my plants. Just tomatoes or peppers and nothing but transplants.
KennyP