The rose of Sharon is usually more than willing to spread and fill in its area, however, if you want a new plant without digging up your existing plant, one easy way to get it is through cuttings. When you know how to take a cutting of a rose of Sharon, you can propagate new plants easily in your own yard or indoors in a flower pot. With a little preparation beforehand and waiting until the fall, you can take your cutting and have a permanent planting in one to two years.
Place a loose twist tie, or lightly tie a string, onto a few of the stems of your new growth. These will be the new stems in the spring, or tag them during blooming since the rose of Sharon blooms on the current year's growth.
Wait for autumn when the leaves of your rose of Sharon have dropped and the plant has gone dormant. Look over the plant for pencil-thick branches coming off your vigorous, new growth stems which are marked.
Cut the branches you have selected away from the stem near the base of where it separates from the main stem without cutting the main stem.
Trim your stem to nine to 12 inches long with one cut at just below a bud for the base, and the top end cut of the stem being just above a bud. If your stem is long enough you may be able to get more than one usable stem off the same branch.
Remove a thin, one inch long, quarter-inch wide sliver of wood, or bark, near the base of your stem to help aid rooting. This can be done by starting with the blade of your knife at one inch from the base end and pressing the blade toward the tip to peel away the wood. Your cutting is now ready to be planted.