Twins and Growing Edit
All the elixir does, is grant you with twins. You have to sprinkle it on 1 seed in your garden. It is like when you spread fertilizer– but it doesn't operate like fertilizer. The Mandrake Elixir doesn't speed up the process of your seed's development. It is a 100% chance you will get twins, if you use the elixir, but 50% Identical gender Twins, and 50% Fraternal. Once you have picked the seed, and you know you have put the elixir on it, it will give you a choice to 'customize' 1 baby, the other one will be chosen automatically. As always, you will be able to choose the skin color.
When you have twins, sometimes if you play with 1 before the other, they will share items/food. Usually they share all of the time! If you don't take good care of them, they will go potty badly at the same time, causing you to get more nappies.
As said, the only two seeds you can sprinkle it on are the rose and cabbage seeds. Those two seeds grow normally, but you can't sprinkle it on fully grown seeds or Magic Seeds, since they are fully grown when you plant them.