There are four supports for each frame, and each support consists of one 21 in (53 cm) 2x4. Measure and mark where your supports will go with a tape measure and pencil.
[header] How to make a garden shelf [title] Attach frame supports to the back of the frame. [step] Each tier of this shelf will be comprised of one frame. The front and back of the frame are formed by 96 in (2.4 m) 2x4 boards.