I bought the game more than a year ago and only just discovered all the spreadsheets and stuff. At first I just had fun cross breeding at random then decided to keep track in a notebook. I'm actually trying to find as many plants as possible and I figure I'll find the magic plants along the way.
Don't worry about the spreadsheets at first or decorating the nursery, just enjoy the game and play how you want to. That is one of the great things about this game there's not one right way to play.