Do i need a passive power up to finish the quest like some of the stars require?
Pots change what they do based on the color. There's only 3 outcomes, so if you get the wrong vegetable, first remove it, then change the empty pot to the previous color, then put in whatever it gave you inside, and use magic again. This will give you the third vegetable every time.
If you just magic a pot back and forth with the same item in it, it will keep giving you the same two things.