Skip to main content
Penstemon barrettiae (Barrett's Penstemon)
1 / 8
© Peter Zika, some rights reserved (CC-BY-NC) · iNaturalist

Penstemon barrettiae

Barrett's Penstemon

Columbia River Gorge (Pacific Northwest)

At a Glance

TypeShrub
FoliageEvergreen
Height8-16 inches (20-40 cm)
Width18-30 inches (45-75 cm)
Maturity3 years

Growing Zones

USDA Hardiness Zones

6 - 9
These zones indicate the coldest temperatures this plant can typically survive.
What's my zone? →
Frost Tolerancehardy

Overview

A subshrubby perennial reaching 8-16 inches (20-40 cm) tall from a woody base, forming a low mound or trailing mat 18-30 inches (45-75 cm) wide. Leaves evergreen, opposite, lance-shaped to oblong, 1.5-3 inches (4-7.5 cm) long, blue-green to glaucous, with smooth or sparsely toothed margins and a slightly waxy surface. Inflorescences erect terminal panicles 6-10 inches (15-25 cm) tall with 10-30 tubular flowers held at the stem tips. Each flower 1-1.25 inches (2.5-3 cm) long, lavender to rose-purple with a paler throat marked by darker guidelines, two-lipped with the lower lip flaring outward. Capsules 0.25-0.4 inch (6-10 mm), ripening in summer. Plants form a slowly expanding woody-based mound and may root where lower stems contact moist soil. Drought-deciduous lower leaves drop during summer in hot dry sites; upper foliage persists year-round in zones 6-9. Range is restricted to a small area of the Columbia River Gorge along the Oregon-Washington border, where the species is listed as imperiled.

Native Range

Endemic to the Columbia River Gorge of Oregon and Washington, primarily on basalt cliffs, talus slopes, and rocky riverbanks at 100 to 1,500 feet (30-460 m) elevation. The species occurs on fewer than 50 sites within a range of approximately 50 miles (80 km).

Suggested Uses

Commonly planted in rock gardens, dry stone walls, and sloped sites with sharp drainage at 18-24 inch (45-60 cm) spacing. Suitable for containers of at least 3 gallons (11 L) with at least 50% mineral grit and no winter saturation. The species is listed as imperiled in Oregon and Washington; cultivated material from native plant nurseries supports conservation rather than wild collection.

How to Identify

Distinguished from related Penstemon species by glaucous, waxy blue-green evergreen leaves and a mounding subshrubby habit on rocky basalt habitats. Flowers lavender to rose-purple, larger than those of P. cardwellii (1 inch / 2.5 cm) and held in narrow erect panicles rather than open clusters. Endemic distribution further separates the species from morphologically similar relatives.

Appearance

Size & Dimensions

Height8" - 1'4"
Width/Spread1'6" - 2'6"

Reaches mature size in approximately 3 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~5 weeks
J
F
M
A
M
J
J
A
S
O
N
D
April through June; lower-elevation populations along the Columbia River bloom in April-May, higher-elevation populations into June. Each panicle holds open flowers for 3-4 weeks; the full bloom period in a stand extends 4-6 weeks.

Detailed Descriptions

Flower Description

lavender to rose-purple

Foliage Description

blue-green to glaucous

Growing Conditions

Sun Requirements

Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)
357912
Soil Types
Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

2-3 years to mature size

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Plant container-grown specimens in autumn or early spring into sharply draining gritty soil with at least 50% mineral content. Water weekly during the first growing season; established plants tolerate periods of 4-6 weeks without rain. Soils that retain moisture at the crown cause root rot within one season. Aphids appear on flower stems in warm springs but disappear with summer heat. Plants persist 6-10 years in suitable rocky sites; lifespan in heavy or moisture-retentive soil rarely exceeds 2-3 years. Cuttings root in 4-6 weeks in late summer and are the typical propagation method for cultivated material.

Pruning

Cut spent flower stems to the topmost healthy leaves after flowering in early summer. Light shaping can be done in early spring before new growth emerges; older wood does not regrow when cut hard, so removal is limited to no more than one-third of stem length per year. Damaged stems can be removed at the woody base at any time.

Pruning Schedule

J
F
M
A
M
J
J
A
S
O
N
D
summerearly spring

Maintenance Level

low

Container Growing

✓ Suitable for container growing

Minimum container size: 3 gallons

⚠️ Toxicity Warning

Non-toxic