You can purchase seed starting trays at a home and garden center, or you can make trays out of common household items for a fraction of the cost. Seed starting trays are used to germinate seeds and establish seedlings before the outdoor growing season begins. While you can use any planting container to start seeds, trays make better use of space, allowing you to start more seeds in a smaller area.
Hammer a nail several times through the bottom of aluminum pie or cake pans. This will create drainage holes in the pan. Disposable pans work well for this, but you can use older pie and cake pans if they are already in your kitchen.
Split corrugated cardboard egg cartons in half, separating the lid from the egg section of the carton. You can use both halves of the egg carton to start plants.
Line a beer or soda cardboard flat with plastic wrap. Poke several holes in the bottom for drainage with a nail or knife. Fill with potting soil and plant seeds over the surface of the flat.