Choose tiles with coordinating designs or colors. For instance, you could choose three solid green tiles and two tiles with a green damask or flower design on them. Always choose at least one solid colored tile for the bottom of your planter.
Lay out your tiles and clean them off with a mild cleanser. This removes dust and oil that could prevent the sealer from drying or keep the tiles from adhering to one another. Let them dry for about an hour.
Paint the undecorated side and edges of each tile with sealer. This prevents the moisture from the plant soil from seeping into the tile and causing mold. Allow the sealer to dry overnight.
Run a bead of tile cement up the left edge of one of your tiles. Press the right edge of a second tile into the cement, positioning the tiles to form a 90-degree angle. Add the other two tiles the same way, forming a hollow square box.
Draw a bead of tile cement over the top edge of your hollow square box. Press your fifth tile into the bead as a lid for the box. Allow the planter to dry for about 24 hours and plant as desired.