Secure stacks of terra-cotta pots so they don't stick together or tilt dangerously. Drill 1/2-inch holes, spaced to fit pot diameters, through a 1-by-10 (atop scrap lumber). Apply wood glue to bottom inch of 1/2-inch dowels no longer than 18 inches. Insert in holes, squaring with base; let dry overnight. Sandwich 1-by-12-inch corrugated-cardboard strips between pots on rack.