Planters can come in many shapes and sizes. Most planters are decorative boxes built to display potted plants. Planters are usually built out of 2x4s and 2x6s with a shelf or false bottom set about 12”-16” below the top to support the plants. This is so plants can be exchanged as necessary while providing the illusion that they are growing directly out of the planters. The visible surfaces of the planters are covered in decking or fascia material for appearance. If you are planning on filling the planters with soil outside of a pot you should line the interior of the planter with poly sheeting to protect the wood. Planters are often used in combination with benches to present a coordinated design.