Prepare your perennials for winter to ensure a vibrant showing in spring. Winterizing butterfly bushes (Buddleia davidii) provides for the plant's safety and continued health during its dormant phase. Winterizing butterfly bushes requires only a small amount of time, and the effort will pay off when the plants return in the spring with beautiful, fragrant blooms.
Remove any debris and weeds growing around the base of the butterfly bush.
Cut the butterfly bush back to around 4 feet tall, or all the way back to the ground. Hardy perennials, butterfly bush will enter a dormant phase during the winter in most planting zones. The best time for a final pruning of butterfly bush is late fall. If you choose to trim the butterfly bush back to ground level, placing a stake or other type of marker at the site to remind you of its location when spring arrives.
Add mulch around the base of the butterfly bush to keep roots from drying out over the winter. A sun-loving perennial, butterfly bush roots are more prone to rot. Too much mulch on the root system can promote rot so apply only a thin layer of mulch around the plant. Use a variety of natural items for mulch, such as sawdust, leaves, wood chips or grass clippings. Arrange mulch to within 1 to 2 inches of the base of the butterfly bush.
Dispose of any pruned branches and any weeds pulled from around the butterfly bush. Shred them for mulch or throw them onto a compost pile. Break up any large, woody branches before composting.