In a saucepan over low heat, combine pomegranate juice and sugar. Stir until dissolved, about 5 minutes. Do not allow to boil.
Remove from heat and add hibiscus tea bags. Allow to cool and steep, about 20 minutes. Squeeze excess liquid from tea bags and discard.
Transfer grenadine into a glass jar or squirt bottle.
Keep chilled until ready to use, for up to 1 week.