Hi
I have sprouted Hibiscus seeds that were 3 years old stored in my fridge all that time. I finally started them 3 years ago. Here is how.
Soak in hand hot water over night. The next day place seeds in a moist paper towel inserted in a ziplock baggy. Place the bag in the fridge for 1 week. After 1 week place them in room temp. I used the top of my fridge where it is warmer. Mine sprouted in 5 days.
Sprouting seeds ready to plant
3 colors of Hardy Hibiscus started from seed.