The impressive flowers of the hardy hibiscus (Hibiscus moscheutos) provide a tropical flair to gardens in U.S. Department of Agriculture plant hardiness zones 5 through 9. A hardy hibiscus can grow up to 3 feet tall, with a spread of over 2 feet. Dividing the plant helps minimize its size while providing a new hibiscus bush for another area in the landscape. Although hibiscuses can tolerate division, you must do so properly and replant the divisions promptly to ensure survival.
Hardy hibiscus doesn't require frequent division, and dividing too often can stress the plant. Ten-year-old, healthy plants respond best to division. Although it's possible to divide hibiscus in spring just as new growth begins, the plant may recover slowly. Waiting until early fall ensures better survival. Hibiscus is actively developing its roots during fall and the cooler weather allows the divided plants to establish without the danger of heat or drought stress.
Minimizing root damage during digging helps the hibiscus recover quickly after division and replanting. When digging around the roots, begin at least 12 inches away from the base of the plant. Dig down below the root system then lift the plant out of the ground. You can rinse away excess soil with water so the roots are easier to see for the dividing process. Small roots will most likely become damaged during digging, but avoid breaking or damaging the main root mass.
A clean cutting tool cuts down on disease risk during division. Rinse a sharp knife in a solution of one part bleach to nine parts water to disinfect it before you begin. Most hardy hibiscus tolerate division into two plants. Cut through the main root mass,, dividing it into two roughly equal-sized pieces. Each division must have both roots and healthy, actively growing top shoots. Trim off any section of the root balls that are badly damaged or appear rotten or diseased.
Almost any garden bed that has well-drained soil that is rich in organic matter can grow a healthy hibiscus plant. Working a 2-inch layer of compost into the top 8 inches of soil before replanting further aids drainage and improves soil quality. The site must also receive full, all-day sunlight to ensure best flowering. When replanting the divisions, plant them at the same depth they were growing at previously. Water the bed thoroughly after replanting so the soil is moistened to the depth of the root zone. Divided plants sometimes suffer minor shock, which results in slight wilting or slow growth. The hibiscus will usually recover if you continue to supply it with 1 to 2 inches of water weekly so the soil doesn't completely dry out.
- Hemera Technologies/Photos.com/Getty Images