Shawn is a firm believer in the raised bed. You may not be worried as he is about unexploded ammunition lurking below, but you still don't know what's in your soil, so the safest bet is to build a bed on top of it. Shawn points to one of their 68 raised beds (that will be home to 114 varieties of plants over the course of the season), and notes how they use recycled plastic lumber, available wherever decking supplies are sold. Sure, pine looks better, but it's a pain to move around. Recycled plastic is lightweight, so if after one year you realize you need to move your garden to a sunnier spot, that's easy. And it will last for decades, where wood might last only a few seasons. To avoid contamination with the soil below, lay landscape fabric down, then a layer of wood chips, then plop your bed on top and pour in the topsoil—or even easier, have someone build a bed for you.