The larger calla lilies come in closed cut (most commonly used) or open cut (very large and beautiful).
Mini calla lilies come in a variety of colors.
Large calla may come with a plastic sleeve. Remove this and cut the stem with a sharp knife before placing in water at least half way up the stem to help hydrate completely. This could be up to six hours for complete hydration. Mini calla come in bunches. Place only 1-2 inches of water for the mini calla.
To make your calla lilies last as long as possible, avoid touching the blooms and handle them as little as possible. Keep them in a cool place, out of direct sunlight and away from fans or drafts.