The hardy hibiscus, also known as the rose mallow can be propagated by division, separating the root ball of a mature plant into separate plants. While separating hardy hibiscus is best done in the spring, fall propagation can be done with a little preparation.
Propagating Plants by Division
Dig up the root ball of a large, fully mature hibiscus plant, taking care not to damage the plant. Remove all excess soil from around the roots.
Look for areas at the base of the stems to identify places where they can be separated at the roots.
Carefully separate the roots of the hibiscus plant by hand, ensuring that there are enough stems in each separated piece to form a new plant. Cut any larger roots with garden shears. Continue this process until all separations are complete.
Transplant the new hibiscus plants into containers filled with potting soil and water thoroughly.
Place the containers indoors in a sunny area or in a greenhouse to protect the plants. Containers are used because hibiscus will generally not survive transplanting outdoors that late in the year except in tropical areas, such as southern Florida.
Transplant your hardy hibiscus plants in the spring, after the risk of frost has passed.