Their square planter boxes are made from tongue and groove siding and put together with wood screws and ring shank nails to ensure durability. Planting in these containers could not be easier or more fun. Put down drain material in the bottom, fill with potting soil, and your favorite planter, and enjoy. Or, simply insert plastic pots filled with flowers for easier clean-up in the fall. August Grove® Finish: Unstained, Size: 17" H x 21" W x 20" D