Pacific Ninebark
Physocarpus capitatus
- Native to:
- Canada, United States
wlcutler
Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Rosaceae
- Genus:
- Physocarpus
- Species:
- Physocarpus capitatus
- USDA Symbol:
- PHCA11
Growth Characteristics
- Life Cycle:
- Perennial
- Growth Habit:
- Shrub
- Height:
- 400 cm
- Light Requirements:
- Full Sun,Part Shade
- Drought Tolerance:
- Medium
- Bloom Months:
- apr,may,jun,jul
- Bloom Colors:
- white, pink
- Landscaping Shrub:
- Yes
Wildlife Benefits
- Bees:
- ★☆☆☆☆ Documented bee visitation (GBIF)
- Butterflies & Moths:
- ★☆☆☆☆ Documented Lepidoptera association (GBIF)
- Caterpillars:
- ★☆☆☆☆ Recorded caterpillar host plant (HOSTS Database)
Keystone Species Ranking
- Caterpillar Keystone:
- ★★★☆☆ Butterfly & moth species supported by this genus (NWF)
Host Plant for Caterpillars
Eulithis xylina, hibiscus Quaker (Orthosia hibisci), Obliquebanded leafroller (Choristoneura rosaceana)
Garden & Ecology Notes
- Wildlife Value:
- birds, bees, butterflies
- Deer Resistant:
- Yes
- Fall Color:
- yellow, bronze
- Fire Ecology:
- Fire adapted — tolerates or benefits from fire
- Fire Notes:
- Resprouts vigorously from root crown after fire. Common in fire-maintained riparian and woodland edges.
Soil Requirements
- Soil Type:
- rich, well-drained loamy soil
- pH:
- 5.5 - 7.0 (slightly acidic to neutral)
- Drainage:
- tolerates poor drainage
- Moisture:
- consistently moist
- Notes:
- prefers riparian zones and wetland edges
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 30–90 days
- Germination Time:
- 14–60 days
- Notes:
- Seeds require light for germination. Cold stratification improves germination rates significantly.
The above propagation data sourced from Claude AI
Pre-treatment: Sow seed into trays filled with stabilized medium plugs (Q-plugs). Seal trays inside plastic bags and refrigerate at 1 to 3 °C for 30 days. Check trays weekly and keep moist. If mold is evident, treat with 1% hydrogen peroxide.
Establishment: Pacific ninebark is found primarily west of the British Columbia Coast, Cascade, and Sierra Nevada Mountain Ranges from extreme southeast Alaska to central California. Habitats include streambanks, lake margins, and swampy areas or openings in moist woods.
Source: npn.rngr.net
ORGHPS Germination Guide: Sow @ 20C. Germinates within 3 months.