Window box flowers create additional space in which to grow plants and flowers. Window box flowers are a beautiful addition to any house whose owner has a green thumb. There are several different materials for window box flowers. One that popular is wooden window box flowers. Wooden window box flowers can be purchased, but you can make your own for less money with a few basic tools and materials. Wooden window boxes are often made out of cedar and add natural beauty to any home’s exterior. Plastic inserts are used to line the wooden box to prevent the wood from rotting.