Fruit Seeds give you the chance to feed two crystals to the plant. Other types of seeds allow only one crystal. Having your plant eat two crystals isn't really a bonus, though. It only means that there are more combinations to play with so you get a greater variety of results because instead of 8 possible crystals, you now have 8 * 8 = 64 possible crystal choices. I don't know any off the top of my head, but there are gardening sites out there that will tell you what crystals get what results so that you can narrow down what you might get out of your flower pots. Good Luck.