Decide where you want your outdoor planter to go and what type of plants you want to grow. Gather the necessary tools and place them near your work space.
Determine the size of your planter box, then measure the garden area you will need. Remove 2 inches of soil and sod from the ground. Rake the area level.
If you are building a portable outdoor planter, you don't need to remove the layer of soil and sod. Instead, add a bottom layer of wood and handles to the outside of the box.
Measure and cut planks of wood to meet the criteria of your design. If you plan to grow tall plants, increase the height of the planter box.
Drill pilot holes and screw the boards together at the corners. Use a carpenter's square to make the box plumb.
Once the box is at the height you want, insert it in the garden area you cleared. Fill the box with potting soil, then add plants.