Q: I mean "on" St. Patrick's Day.
A: I'm not sure about the Dutch thing, but maybe this will help you too. Orange represents the Irish Protestants. They wear orange on St. Patrick's Day in protest to the Catholics. The green symbolizes the Catholic Irish, while Orange represents the Protestant Irish. Although Green, has become a "national" color, so the Protestants wear Orange to remind the world that Ireland is more than just Catholic.