Board Thread:FarmVille (game discussion)/@comment-25076303-20140618023231/@comment-409884-20140618113025

If you mouse-over or click the word "unlock" the game will tell you what you you have to accomplish before that crop is unlocked

Example: to unlock Super Strawberry you have to have mastered, all 3-stars, Strawberry.

If it is a Musical note crop -- it will tell you what the previous musical note crop needs to be mastered before it, same with the Space themed crops as well as the other specific themed crops.