Combine half of cabbage and half of salt in large bowl. Forcefully knead salt into cabbage until cabbage just begins to soften, about 3 minutes. Add remaining cabbage and salt and continue kneading until all cabbage has softened and begins to give off moisture, about 3 minutes. Stir in juniper berries.

Transfer cabbage and any accumulated liquid to sterilized 1-gallon ceramic crock, pressing down firmly with clean fist or sterilized flat headed potato masher to eliminate air pockets. Top cabbage with clean plate just small enough to fit inside crock and weigh plate down with clean rock or quart jar filled with water. Cover with triple layer of cheesecloth, securing in place with rubber band. Let ferment at room temperature, 65 to 75 degrees, for 2 hours.

Remove cheesecloth and weight, and press plate firmly onto cabbage. Replace weight and cheesecloth and let ferment 2 more hours. Repeat process twice more, or until cabbage is fully submerged under brine. (If brine doesn't completely submerge cabbage within 24 hours, cover cabbage with mixture of 1 cup water and teaspoon salt).

Check cabbage every 2 days, pressing down cabbage to keep it submerged (top off with additional brine, made following instructions in step 3, as needed). Let ferment until sauerkraut has reached desired level of fermentation, 5 to 10 days. Transfer sauerkraut and brine to glass jars with tight-fitting lids and refrigerate. Sauerkraut can be refrigerated for up to 2 months.