FWIW Dept If you live in an area where there is a lot of rocks, build your raised beds with rocks The Pilgrims did and they are still in use. Pressure Treated Lumber. Buy what you need, Allow to air dry for at least 3 months in summer. Apply at least 3 coats of a real good exterior house paint. When cutting this stuff wear a real good particle mask and gloves The cheap throw away mask are not good enough. There are quite a few decking carpenters around here dieing of Aresenic poisoning Cement Blocks AKA Cement Masonary Units. Use a plastic liner between inside of block a garden soil, This will have a lime leaching. Creosote RR Ties. Use some plastic about the same material as a pool liner between the inside of your frame and growing soil. There is a fiberglass "Fencing Board" that could be used. This stuff is brittle when cold. Tips from a flat bed gardener. Byron