Earlier this year, Gardening Australia ran a segment on how to propagate cardamom from store bought pods.
True cardamom (Elettaria cardamomum) is very difficult to find in nurseries in Australia, with most nurseries selling the false variety, AKA Cardamom Ginger or Dwarf Cardamom (Alpinia nutans or Alpinia mutica). The false varieties have cardamom-scented leaves and are a useful landscaping plants, but will not produce the pods you can use in cooking.
Zacaconia Tropical Gardens 