Diy Wagon Planter . Wood shims to create a box. Add a layer of rocks to the bottom of the wagon to assist with drainage. DIY Crate Wagon Planter, Display, Fun! Prodigal Pieces from prodigalpieces.com This is an important step that you won’t want to forget, and one of the keys to the success of your container garden. 22 creative wagon planter ideas + whiskey barrels and wheels | diy garden#diygarden #gardenideas Add a layer of good potting soil or dirt to the wagon.