Break the egg toward the narrow top end, leaving a large portion of the shell intact. Rinse it with water, and carefully poke a drainage hole in the bottom with a sharp knife. Fill it with moist soil, and plant your seed. The egg carton is a handy way to keep the shells upright and serves as a tray to catch water. When seedlings are ready, gently crush each shell, and plant.
Roots grow through the cracks, and the shells add a small amount of calcium to the soil.
Another convenient container is a newspaper pot. A tool called a Paper Pot Maker aids in folding a strip of paper into a small vessel perfectly sized for one large seed or several small ones. The pot drains easily, and the newspaper does not deteriorate when damp. If you choose to start a lot of seeds, a small greenhouse keeps the project contained and allows you to regulate several factors that are important to germination. Problems arise when they start to overwater and expose the new seedlings to cool air right away.