Rinse the glass jar in hot water and dry. To ensure the spices do not float to the top of the glass, add the juniper berries first and then the salted cabbage on top. The jar must be filled with vigorous pressure. The mix must be pounded down after every layer. The aim is to release even more liquid out of the cabbage. The more juice, the better the flavor. There must not be any oxygen between the layers.
Do not fill the jar to the brim! The fermenting process produces gas, which could cause the jar to overflow.