Minecraft wiki entry for Development_versions, associated text: No longer gives instant growth – instead, each use advances one growth stage:
Crops require seven bone meal.
Saplings and Cocoa Beans require two bone meal to grow into Trees and Cocoas, respectively.
Brown and Red Mushrooms still grow into Huge Mushrooms instantly.
Gives off green particles when used.
Note: Dinnerbone has stated that he still has to balance out this new bonemeal growth system.[14]