We decided to free our snails several weeks ago. Upon releasing them to the world, it soon became apparent during cage cleaning that they’d left behind a gift – a clutch of eggs.
Garden snail eggs usually hatch after 2 to 4 weeks in the soil. They need an immediate source of calcium after hatching (to build their shells), so they eat their egg casing and possibly any other snail eggs they encounter. It will take about three weeks for them to appear like small land snails (without the translucent shell color) but it takes up to a full year for them to be sexually mature. As adults and hermaphrodites, they can lay eggs as much as once a month. Garden snails can live for several years.
Since most gardeners consider garden snails to be a nuisance species, it is worth considering if they provide any benefit to an ecosystem. Of course the answer is yes: they are a part of the food chain and provide nutrition for other species, and they break down decaying plant matter. Apparently, they also are more likely to consume plants and leaves that are sick and dying than those which are healthy and robust.