“Must purchase Flower Garden” error message when buying items
If you get an error when you attempt to purchase an item from the Flower Shop saying that you must first purchase Flower Garden to buy that item, it means the App Store doesn’t have a record of you downloading Flower Garden with that account.
Go to the iPhone Settings app and view the Store category. There, make sure you log in with the same account you initially used to buy Flower Garden.
Otherwise, if you don’t remember the initial account you used, the only solution is to delete Flower Garden and re-download it with your current account (if you do a backup through iTunes first, you should be able to restore your garden to the exact state it was in before).