People often find dividing Rose of Sharon bushes helpful when they are becoming too big to manage or aren't flowering like they used to, but division is also a good way to add more Rose of Sharon to your own yard or to share the plant with friends and family. If you don't know how to divide a Rose of Sharon bush, don't worry. It's a simple process that can be done in less than a day with nothing more than regular watering needed afterwards.
Wait until 30 to 45 days before the first frost for your region before you begin. Trim the entire height of your Rose of Sharon bush to approximately 18-24 inches.
Dig up your existing bush to bring up the whole root ball. Divide the root ball in half once and then a second time to create four quarter pieces of your plant.
Make sure each portion of the plant has roots attached to it. If the root ball sections are larger than a grapefruit, then you can divide these quarter pieces in half as well.
Plant each section into your yard or garden into holes as deep as the root ball and three times as wide. Fill in each hole with well-broken-up soil, adding compost or garden soil if needed to increase the soil's lightness and/or drainage.
Mulch around the base of the individual plants and water them well to keep the soil moist for the first month. In the spring each division should begin with regular growth and may or may not flower the first year.
Add 1 tablespoon of 10-10-10 fertilizer to your plants each spring for each foot in height of your plant. An additional dose in midsummer can also be beneficial, but is not necessary.