Rose of sharon (sometimes called althea) is a vigorous, blooming hibiscus shrub. It grows to 10 feet tall and has shiny leaves and either single or double blooms. Although many gardeners find rose of sharon beautiful, not everyone does. Whether you want reduce the number of rose of sharon in your garden, wipe them out altogether, or simply keep suckers under control, you have a bit of battle on your hands. The same persistence that makes rose of sharon an easy to grow plant also makes it a persistent weed when you don't want it in your garden. However, if you are more persistent than the plant, it will eventually stop sending up shoots.
Cut the rose of sharon shrub down to the soil, using pruning shears, lopers or a chain saw. Remove all branches and suckers.
Dig up all the plant's roots, using a shovel and pruning shears. Depending upon how mature the rose of sharon was, you may not be able to dig deep enough to find all the roots, but do your best.
Dig up shoots as they spring up from the soil, using a shovel and pruning shears. Mow down new shoots, alternatively. This method will take longer than digging up the roots, but is easier on the gardener.
Spray new shoots with an herbicide like Roundup, if you wish. Follow the manufacturer's directions carefully. This is best done on a sunny day, and care must be taken not to spray desirable plants. It will take several applications to completely get rid of the rose of sharon shoots.
Lay down newspapers in the area where the rose of sharon was, Place soil or compost on top of the newspaper, then a layer of black plastic. Once the roots are already weakened by removing the mother plant and digging up the most persistent shoots, this method should eradicate most of the remaining roots. Allow the plastic to remain over the soil for at least one season and preferably one year.