Juniper Berries, whole
Common juniper is a small evergreen tree that is related to cedar, cypress and other conifers. The mature, dark-colored cones, or berries, are used to lend a slightly citrus and pine-like flavor to foods and beverages. In Northern Europe, juniper berries are used as a spice to season game meats and sauerkraut, as well as beer. The berries are also the key flavoring agent in gin.
The amount you add to your beer will depend on trial and error, but as a general rule, up to 1 ounce in 5 gallons is recommended. Crush the berries and add in the last 15 minutes of the boil.