How does one prepare soil to plant salad greens?

I'd like to set up a container to plant some salad greens with the kids, but I am a bit uncertain whether potting soil from stores or soil from my garden may contain too many chemicals (pesticides, fertilizers etc). Any suggestions?

I have had the very best luck with something called Dr. Earth's Organic Potting Soil. I can't tell you how well my plants have responded to this one.

Thank you! I'll look into Dr. Earth's Organic soil.

Have you ever tried to rehabilitate your own soil into "clean" organic soil?