The urban farm Brooklyn Grange defies expectation. For one thing, it’s in Queens. For another, it’s planted on the roof of the hulking Standard Motor Products Building, where, beginning June 1 and every subsequent Wednesday in season, from 2 to 7 p.m., the harvest will be sold at a makeshift stand in the lobby. Load up on French breakfast radishes and lollo rossa lettuce, then head upstairs to glimpse the improbable acre under cultivation (37-18 Northern Blvd., Long Island City).