Photo: Stickpen — Public domain · source
Survives zone 5 through 9
Harvest calendar
Best planted in early spring after your last frost, or in fall before the ground freezes, depending on your climate.
A wild western black raspberry — closely related to the cultivated black raspberry R. occidentalis — valued in its native range for well-flavoured black-to-dark-purple fruit used fresh, in pies and jams, or dried; young peeled spring shoots can also be eaten raw or cooked like asparagus, and the leaves make a vitamin C-rich tea.
- Hardiness
- Zone 5–9
- Habit
- Shrub
- Edible part
- Fruit
- Ripens
- Summer–autumn
- Mature size
- Arching shrub 1–2 m, the canes blue-bloomed
- Light
- Full sun to partial
- Soil pH
- 6.0–7.0 (near-neutral)
- Environment
- Temperate
- Native range
- Western North America, from southwestern British Columbia and southeastern Alaska south through Washington, Oregon and California to the Sierra Nevada, and inland through Idaho, Montana, Nevada, Utah, Arizona and New Mexico — typically in open woods, forest clearings, streambanks and other disturbed or early-successional ground.
- Status
- Wild
- Years to fruit
- 2–4 yrs
- Growth speed
- Fast — vigorous arching canes reaching up to 2–2.5 m in a single season, typical of wild black raspberries.
- Spacing
- 120 cm (47 in) apart — about 1.4 m² (16 sq ft) per plant
- Leaf shape
- Compound leaves typically with 3 (occasionally 5) sharply toothed, whitish-downy-beneath leaflets, carried on canes covered with a distinctive powdery blue-white bloom and armed with stout, hooked prickles.
- Root system
- Perennial crown with rhizome-like roots that resprout vigorously after fire or cutting, combined with tip-layering of arching canes — together these let it form spreading, thicket-forming colonies, especially on disturbed or recently burned ground.
- Fruit description
- A raspberry-type fruit — hollow-cored, separating cleanly from its receptacle when picked, like a true black raspberry — that ripens from red through purple to dark purplish-black, roughly 1 cm across, described as well-flavoured and used for fresh eating, pies, jams and syrups.
- Propagation
- Seed needs 90 days of warm stratification followed by 90 days of cold stratification before it will germinate reliably; more commonly propagated vegetatively by tip layering (rooting the down-curving cane tips), by division of the crown, or from hardwood/half-ripe cuttings.
- Pollination
- Self-fertile
The edible parts listed above are a starting point, not a field guide. Identify a plant with certainty — ideally against a local authority — before eating any part of it, and read the full disclaimer. Spotted something wrong? Report it.
Growing guide
Fertilizing. As an early-successional shrub of disturbed sites and open forest, it is not demanding of rich soil; a spring mulch of compost or well-rotted manure and consistent moisture do more for fruiting than heavy fertilizer, and it dislikes exposed, windy positions.
How it spreads. A vigorous colonizer of disturbed ground — spreads both by tip-layering (arching primocanes root at the tip each autumn to form new plants, exactly as in black raspberry, R. occidentalis) and by resprouting from a perennial rootstock/rhizome system after fire or other disturbance, often reaching peak density 5–10 years after a disturbance event on suitable moist sites; can form dense, thicket-like colonies but is not generally listed as a regulated noxious weed.
Growing tips. Biennial floricane habit like other black/purple raspberries — canes grow vegetatively their first year, fruit in the second, then die and should be cut out. Canes are noticeably armed with stout, curved (hooked) prickles and are covered in a powdery, whitish-blue waxy bloom that rubs off with a thumb, distinctive among Rubus and the source of the 'whitebark' name. Prefers moist, well-drained soil in full sun to light woodland shade and specifically dislikes windy sites; hardy through USDA zones 5-9, reflecting its wide elevational and latitudinal range in western mountains.
Grow journal
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