where is the trophy garden in pokemon platinum ds

[pokemonplayer]

where is the trophy garden in pokemon platinum nintendo ds

[Zidarose]

The Trophy Garden is found by going through the Pokemon Mansion, literally walking straight through it, on Route 212.

The Mansion itself runs along the upper portion of Route 212, directly south of Hearthome City. Just follow the fence south until it breaks off to the right. Go through the gap and head up into the Mansion. Be sure to talk to Mr. Backlot, found in the first room down the right-hand corridor, to potentially get some rare Pokemon.

Our guide has more details:
Pokemon Platinum Trophy Garden Guide