Home Postcode finder SA Geranium Plains Geranium Plains postcode SA Geranium Plains is a locality in South Australia covered by postcode 5381. Postcode 5381 State or territory South Australia (SA) Region Sa Subs Near 1 Add a free Geranium Plains business listing Be the first listing in Geranium Plains Common questionsWhat is the postcode for Geranium Plains?Geranium Plains, SA has the postcode 5381.What state is Geranium Plains in?Geranium Plains is in South Australia (SA).Does postcode 5381 cover more than one suburb?Yes. Postcode 5381 covers 9 localities, so the postcode alone does not identify Geranium Plains. Browse other postcodes in South Australia, or widen the search to every Australian postcode.