You can't. It is specific to Platinum.
Chat with our AI personalities
It is impossible to find the Gracidea Flower in Pokemon Diamond and Pearl. It is available in Platinum.
If I'm correct, the Gracidea flower cannot be obtained in Pokemon Diamond. Sorry! (Note: The Gracidea can be obtained in Pokemon Platinum.)
you can't you can only get it on Pokemon platinum
The gracidea flower item cannot be obtained in Pokemon Diamond, since Shaymin's Sky Forme is only available in Platinum and later games.
First you need to get the Shaymin from the 11th movie mystery gift event. Then (in Diamond/Pearl) go to the flower shop in Floaroma town. talk to one of the girls and she will give you a Gracidea flower. In HG and SS, you need that 11th movie Shaymin and go to the flower shop in Goldenrod city (northeastern house, near corner)