The maturity bar is comprised of two parts: the egg stage (to the left of the green line one-fifth of the way down the bar), and the frog stage (to the right of the green line). There is no tadpole stage: frogs hatch fully-formed, although tiny, from the frog eggs. The egg hatches by swelling up before popping open like a bubble, releasing the baby frog which it contains. In the egg stage, the player can wait for the egg to develop into a frog (20% of the whole growth time), or use the stated number of potions to grow the frog towards being an adult at four hours per potion. In the frog stage, the player may also use up to the stated number of potions to mature the frog at four hours per potion. The player can also take the frog to the pond mini-game and reduce time to maturity by feeding the frog dragonflies. Once the frog is fully mature, potions and dragonflies will not cause any further growth, instead they will make the frog happier.
Only mature (and tamed) frogs can be bred, gifted to another user, or used in mini-games such as Frog Racing or Puzzle. Immature hatched frogs can be taken to the Pond or cataloged. Frogs of any maturity, including egg, can be sold, although maturity of a frog is a factor affecting the frog's selling value. Eggs cannot be moved out of the nursery habitat unless the Babyproof Kit is purchased from the Pro Shop, but immature hatched frogs can be moved to other habitats.