momofmany-
The plant itself has to be perfect in order to count- you could get a perfect apple off of an outstanding apple tree, so you actually have to have a perfect plant in the ground.
Each opportunity has to be different in order to count towards your multiplier. Skill opportunities are the ones that you can accept/cancel, such as deliver so many fruit to so and so...I don't believe that Master planter, etc. count towards the multiplier. Special opportunities are the ones around town like chess tournament, eating contest, etc.
Each perfect plant, fish, recipe count as .01 towards your multiplier, so your apple, grape, lettuce (each one perfect) would bring you .03 onto your multiplier.
I assume you can practice now, I have already started testing myself.