Pour smushed blueberries into 4 (25 ounce) bottles with flip top lids or other air tight bottles. (½ cup blueberries will go into each bottle.)
Using a funnel, pour freshly made hibiscus kombucha into each bottle leaving 1-2" head space.
Let bottles sit out (at 75° - 85°) 3-5 days, making sure to pop the lids each day (or a few times a day) to let out the pressure of the carbon dioxide. Taste each day to test its flavor and fizziness.
Refrigerate when you are happy with the amount of fizz and flavor.