Crush as many clean, empty aluminum cans as needed to fill half of your planter. To crush a can neatly and quickly, place it vertically on a hard surface and step down on it firmly while simultaneously pressing in on the sides with two pencils.
Neatly line the planter box floor with crushed cans. Stack more cans over the existing cans until the planter is halfway full.
Fill the rest of the planter with soil.