When I first read The Garden State, I instantly thought back to the Garden of Eden. The place where God placed Adam and Eve and then kicked them out because of the great sin that they committed.
The garden is defined as the ultimate paradise.
In the beginning of the story, Candide is kicked out of the castle, which we related back to this historical event. my interpretation of the ending was Candide returning back to a paradise of his own. One that is filled with both sin and truth. Allow me to explain myself.
After all that he's gone through, I don't believe that Voltaire means to tell us that in the end we will find paradise. To me he is telling us that whatever the outcome of our lives, it'll have to suffice. Because it is due to our choices and mistakes that we'll end up wherever it is that we'll end up.
Also, the way that the book ends makes me assume that everyone chose to remain oblivious to anything else. Cultivate or Garden. That is all that matters anymore. Maybe I'm wrong thought. I guess that needs further explanation.