Pacific ninebark is a long-lived perennial shrub of the Rose family native to the Pacific Northwest. It grows rapidly with multiple stems achieving 2 to 4 meters in an erect to arching form with angled branches. The reddish papery bark peels off in long thin layers giving rise to the common name. Deciduous leaves that appear alternately along the stem are 3-10 cm long, 3-5 lobed and doubly toothed at the margin. They are deeply veined, shiny dark green above and lighter beneath with fine star-shaped hairs. Fall color is described as rose-brown. Small (4 mm wide), 5-petaled creamy white flowers with pink stamens form dense rounded clusters at the branch terminals. Flowers appear between late April and July. One to four hard shiny pear-shaped yellow seeds form within small fruits that are individually surrounded by dark reddish brown, bell-shaped bracts. These bracts often persist during winter. For a current distribution map, please consult the Plant Profile page for this species on the PLANTS Web site.

Adaptation and Distribution: Pacific ninebark prefers partial shade but tolerates full sun and is adapted to course, medium and fine textured slightly acidic soils. Occupying low to middle elevations in areas with annual precipitation of 50 to 200 cm, this species has low fertility requirements and low drought tolerance. Pacific ninebark is scattered to common west of the Cascades and often abundant in wet areas and on steep north slopes of the coastal mountains. Habitats include streambanks, lake margins, and swampy areas or openings in moist woods. Occasionally, Pacific ninebark is found in coastal marsh lands and meadows or at drier shrubby sites. Pacific ninebark occurs primarily west of the British Columbia Coast, Cascade, and Sierra Nevada Mountain Ranges from extreme southeast Alaska to central California. It is less prevalent east of the Cascades where its range extends along the Columbia, Snake and Clearwater Rivers into Idaho and overlaps with that of mallow ninebark (Physocarpus malvaceus).

Also known as Physocarpus opulifolius (L.) Maxim. var. tomentellus (Ser.) Boivin and Spiraea capitatus Kursh.

Physocarpus capitatus (Pursh) Kuntze:
China (Asia)
United States (North America)

Canada

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Global Range: Southeastern Alaska to California.

Comments: Moist woodlands and rocky slopes.

Pacific ninebark is typically propagated by seed (requiring 2 to 4 months cold stratification) or is rooted from softwood or hardwood cuttings. There are 43750 seeds per ounce with viability ranging from below 50% to nearly 100%. Softwood cuttings taken in spring may be grown under mist, whereas dormant hardwood cuttings may be planted directly in the field as live stakes or fascines. Autumn is the best time to transplant cuttings or rooted stock. Mulching improves establishment.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Species: 1
Species With Barcodes: 1

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: NNR - Unranked

Rounded Global Status Rank: G5 - Secure

Reasons: Common to occasional in westernmost North America, with thousands of occurrences.

Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status (e.g. threatened or endangered species, state noxious status, and wetland indicator values).

The genus is relatively free of insect pests and diseases although susceptibility to aphids and powdery mildew has been reported. Flower and seed eating specialist insects are known to occur on common ninebark (Physocarpus opulifolius), a native of the eastern United States.

© Province of British Columbia

Pacific ninebark is routinely available in containers or bare-root from west coast native plant nurseries. There is a prostrate ornamental cultivar named ‘Tilden Park’ that grows to a height of 4-5 feet.

Pacific ninebark spreads slowly either by seed or by root sprouting. Concerns are minimal, except for possible toxicity.

Nursery plantings of Pacific ninebark can be as dense as 1200 plants per acre in soil at least 20 in. deep. Consider supplemental irrigation during establishment year or years with low rainfall.

Pacific ninebark’s fibrous roots and capacity to root from un-rooted cuttings make it suitable for soil bioengineering techniques including live stakes, fascines and brush mats. It is particularly valuable for streambank and lakeshore stabilization applications. Pacific ninebark provides good cover and nesting sites for birds and small mammals but has low palatability when browsed by deer, elk and bear. It has ornamental value for the wild garden or open woodland. Although considered toxic by some, Pacific ninebark was used as an emetic, purgative and laxative by Native Americans.