Illustration
Pacific Ninebark
Physocarpus capitatus
Also called western ninebark
Pacific Ninebark blooms from May through June.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Pacific Ninebark
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 5–8. Expect it to reach about 10 ft tall and 7 ft wide at maturity, in roughly 4 years (a house reading).
Pets
- Not yet checked for pets.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
No toxicity note is on file for Pacific Ninebark. That is not a clearance: check its safety for people and pets before planting.
What was checked
Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Pacific Ninebark
Plant Pacific Ninebark in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 6, the middle of its hardy zones 5 to 8, spring means March to May and fall means August or September. Once settled, it blooms from May to June.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Pacific Ninebark get?
10 fttall5 ft 7 inan adult7 ftwideSee Pacific Ninebark in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Pacific Ninebark
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Pacific Ninebark about 7 ft apart, center to center, so each plant has room to reach its full width.
Add Pacific Ninebark to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Pacific Ninebark's height, spread, hardiness zones, sun, water, bloom months and color and trait tags were checked against 8 published sources on November 5, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- Oregon State Universityheight, hardiness zones, sun, water and bloom months and color
- plantdatabase.kpu.caKwantlen Polytechnic Universityheight, spread, sun, water and bloom months and color
- wnps.orgWashington Native Plant Societyheight, sun, water, bloom months and color and trait tags
- burkeherbarium.orgUniversity of Washington Burke Herbariumheight, bloom months and color and trait tags
- calfloranursery.comCalifornia Flora Nurseryheight, spread, sun and water
- watershednursery.comThe Watershed Nursery Cooperativeheight, spread, sun and water
- kitsapcd.orgKitsap Conservation Districtheight, spread and water
- plantoregon.comPlant Oregonheight, hardiness zones and water
How the checking works, and what each standard covers, is on the verified plants page.
Where it grows wild
Native to 5 states and 1 province
United States: Alaska, California, Idaho, Oregon, Washington
Canada: British Columbia
Recorded growing wild in 85 counties.
Range data from the World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 4.0, adapted) and USDA PLANTS. How the native range is credited.
Explore similar plants
You might also like
Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.