Physocarpus / Ninebark
Highly ornamental shrubs offering four seasons of interest
The Physocarpus genus contains highly ornamental, broadleaf, deciduous shrubs, commonly called ninebarks, grown for their graceful branches dense with colorful, maple-like foliage, which can be emerald green, gold, amber, or inky purple and usually exhibits fall color. Spherical clusters of small white to pink flowers bloom in spring or summer, followed by showy, bright, berry-like seed capsules. Honey bees, native bees, and butterflies love the flowers, and songbirds enjoy the seeds throughout winter. The shrubs are also appreciated, and named for, their attractive peeling bark, which exfoliates in “nine” long, sinuous layers, an attractive winter feature.
Physocarpus is a small genus of about 10 species. Most are large, bushy, multi-stemmed, suckering shrubs that grow about 6 to 12 feet tall and wide, but some are smaller, typically staying about 5 to 6 feet tall, with a few varieties only reaching 3 to 4 feet tall. Three species of horticultural importance are P. alternans (dwarf ninebark), a native to western North America, including California; P. capitatus (Pacific ninebark, western ninebark), which is native to the Pacific Northwest; and P. opulifolius (Atlantic ninebark, common ninebark) that is a native shrub with an extensive range from Florida to northern Quebec and westward to the Rocky Mountains.
Ninebarks are tough, cold hardy, and very adaptable. They are easy to grow and generally pest and disease free. Once established, the shrubs are drought tolerant and suitable for xeriscaping. Tall varieties are excellent options for naturalized plantings, hedges, and screens. Smaller varieties are great background plants in flower beds and borders, especially nice in cottage and informal gardens. However, the shrubs can be aggressively pruned immediately after flowering to maintain a desired size and shape.