Home Postcode finder VIC Grass Flat Grass Flat postcode VIC Grass Flat is a locality in Victoria covered by postcode 3409. Postcode 3409 State or territory Victoria (VIC) Region Vic Far Country Add a free Grass Flat business listing Be the first listing in Grass Flat Common questionsWhat is the postcode for Grass Flat?Grass Flat, VIC has the postcode 3409.What state is Grass Flat in?Grass Flat is in Victoria (VIC).Does postcode 3409 cover more than one suburb?Yes. Postcode 3409 covers 12 localities, so the postcode alone does not identify Grass Flat. Browse other postcodes in Victoria, or widen the search to every Australian postcode.