pesticides/herbicides and organic gardening
i'd love to have my first garden be an organic one! however, we moved into this house last year and we've come across areas that were sprayed with herbicide (the previous owners were trying to kill mint), and we also found some ant-poison cones in the ground. i don't want to dig up the entire yard and start over... would a raised-bed garden, with a layer of plastic on the ground, followed by rocks, followed by organic soil, do the trick?? does the plastic take away from the organic-ness? and is there a danger in growing food on top of old soil that we KNOW had poison in it at one point? (and how long does it take for that stuff to disappear anyway? if ever?) thanks for any and all help for this newbie gardener!