Prepare the cabbage for freezing. Remove any damaged or wilted outer leaves, wash under cold running water, and pat dry. Slice cabbage into desired shape: either shreds or wedges.
Bring a large pot of water to a boil. Prepare a mixing bowl with ice water. Once boiling, drop the cabbage into the pot of water. For shredded cabbage, cook for 30 to 60 seconds once the water returns to a boil. For cabbage wedges, increase cook time to 1 to 2 minutes.
Remove the cabbage from the boiling water with a slotted spoon. Plunge it into the bowl of ice water and let cool for a few minutes.
Drain the cabbage and pat dry. Transfer to a baking sheet lined with parchment paper. Spread it out in a single layer.
Place the baking sheet in the freezer, somewhere it can lie flat, for 1 to 2 hours until the cabbage is frozen solid.
Transfer the frozen cabbage to freezer bags, remove as much air as possible, and seal. Store for up to 6 months in the freezer.
Use the cabbage directly from frozen in cooked/hot cabbage dishes like soups.