what type if ' Hibiscus " are you talking about ?....
Rose of Sharon ,, or the perennial kind that freezes back each winter ?
for rose of Sharon ,, you can take cuttings.. root them in 2" of water, then plant out later in the summer
Herbaceous perennial hibiscus can be propagated by dividing clumps in early spring.
Lift the clump out of the soil with a shovel. Use your fingers to work apart the large clump into separate smaller clumps, each with a healthy root mass to support the stems.