With a funnel, add cannabis syrup to a clean glass bottle (either a swing top or one with a cap which can tighten.)
Wash, peel (optionally), and slice ginger into matchstick size pieces and add to bottle. If using hops, add flowers or pellets to a small reusable tea bag. Use a chopstick to push tea bag into bottle.
Top with plain kombucha or water kefir. Leave less than 1 inch (3cm) of head space in the neck of the bottle. Close tightly.
Ferment 4 to 14 days, burping occasionally (over the sink) to release gas buildup.
When you like the flavor and carbonation, move bottle to refrigerator.
Before serving, gently rock (DO NOT SHAKE) the bottle by inverting it a few times. This will allow any sediment to be better incorporated into the beverage when you pour it.
Serve chilled.
Cannabis ingested via food can take a long time to metabolize, sometimes up to 2 hours. Enjoy responsibly and plan accordingly.