According to About.com, most land snails are hermaphrodites. Following courtship in early summer, a pair of snails inseminate each other through a reproductive opening located near the front of the body, resulting in fertilized eggs.
As many as 100 eggs are deposited following mating. Garden snails bury their eggs in warm, moist topsoil. The shell begins to develop when the snail is an embryo. Newly hatched snails are almost transparent and require an immediate source of calcium upon hatching, which is found in the egg casing. Young snails sometimes consume the egg casings of their unhatched siblings. Snails usually reach full size after two or three years.