Gardeners in temperate climate zones outside of the tropics often grow this tropical flowering shrub as an annual or short-lived perennial. Most of the members of the Hibiscus genus are frost tender, although at least one species, the Rose of Sharon Hibiscus (Hibiscus syriacus), is hardy to United States Department of Agriculture Plant Hardiness Zone 5. If you want to save a tropical Hibiscus from frost or snow, you can move it indoors before cold weather strikes.
Fall For Tropical Varieties
Check the USDA Plant Hardiness Zone map to determine the average date of your region’s first fall frost. It is important to move a tropical Hibiscus before that date because a small amount of frost can seriously damage or kill it. If you have planted a Hibiscus in the ground in an unprotected location, dig it up, being careful to include as much of the root system as possible. Transplant it into a pot and move it into a sheltered environment such as a greenhouse or inside your house. Make certain your Hibiscus receives several hours of direct or strong filtered sunlight each day. If that is impossible, hang a fluorescent grow light several inches above the plant. Cut back on watering during the winter and keep your plant relatively dry.
Late Summer For Hardy Hibiscus
Dig up and move a Rose of Sharon Hibiscus in late summer before the weather becomes cooler. Sometimes this plant can become rather unruly and large, so dig up unwanted specimens and move them to a spot away from other Rose of Sharons. Because this plant is hardy in temperatures as low as zero degrees F, dig it up and transplant it to another outdoor location if your winters do not drop into the minus digits. The cold weather will kill your plant’s foliage, but the roots should sprout with new growth when spring arrives. The Virginia Cooperative Extension website reports that this Hibiscus transplants "readily."
Hints and Tips
Before or after digging any Hibiscus variety out of the ground, prune about 1/3 of its foliage. The Virginia Cooperative Extension website recommends cutting off 1/3 of the Rose of Sharon’s branches once a year to promote new growth and maximum flowering. If you move yours in late summer, this would be a good time to also prune it. Clemson University seconds this advice regarding tropical Hibiscus. After the plant has finished blooming for the season, prune it by at least 1/3, concentrating on weak and leggy branches. In areas where hard frosts occur, cut all Hibiscus back to the ground when you transplant them. The plant sends up new shoots in spring and should continue blooming for several years if you repeat your transplanting procedure every year.