A flower box deck project can be done in two ways. The flower box can be created as a free-standing object placed anywhere on the deck to display flowers, or it can be integrated into the deck itself as an extension of the deck. Free-standing flower boxes may be built in various sizes or shapes because they can be moved around the deck, while integrated flower boxes must be custom built to fit into chosen places on the deck.
Choosing hardwood for a deck flower box may be ideal because hardwood is used in quality building for outdoor weather. Examples of hardwood are oak, mahogany and beech. Softwood tends to split easily when drilling, cutting and screwing nails into the wood, but it is a common type of wood. Plywood is a wooden sheet that is strong and flexible at the same time. Although it is ideal for creating boxes for outside conditions because it is waterproof, it is hard to paint and does not look as appealing. It is often used in areas where the wood is not visible.
A flower box for the deck must consist of four sides and a bottom. The front and back sides must be identical and the two ends must be identical to one another to create an even rectangle or square. The bottom of the flower box must measure the length of the box by the width of the ends, so the entire rectangular or square box is covered by the bottom piece. If the flower box is integrated and resting on deck level, the bottom of the box may be the deck surface itself. Nails and a hammer are required to build the box.
Flower boxes need a drainage system whether the box is integrated on the deck or is standing free. A drainage system ensures that excess water in the soil can leave the box, so the flowers do not drown during rainfall or from overwatering. Drill small 1/4-inch holes in the bottom of the box, approximately 1 inch apart. Place 1/4-inch-wide rocks or pebbles into the holes, so soil does not fall out. The excess water seeps out in the cracks between the rocks and drilled holes. Integrated flower boxes can use the deck itself to create the drainage system, while a free-standing flower box should have the drainage system created directly on the bottom panel.