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Penstemon rattanii
Rattan's Penstemon
Coastal northern California and southwestern Oregon
At a Glance
TypePerennial
HabitClumping
FoliageSemi-evergreen
Height12-36 inches (30-90 cm)
Width12-18 inches (30-45 cm)
Maturity4 years
Growing Zones
USDA Hardiness Zones
7 - 9These zones indicate the coldest temperatures this plant can typically survive.
What's my zone? →Frost Tolerancehardy
Overview
Penstemon rattanii is a herbaceous perennial reaching 12-36 inches (30-90 cm) tall and 12-18 inches (30-45 cm) wide. Stems erect, mostly unbranched, four-angled, glabrous to lightly hairy. Leaves opposite, ovate to lanceolate, 1-3 inches (2.5-7.5 cm) long with serrate to dentate margins and finely hairy surfaces; basal leaves narrower and stalked, stem leaves sessile or short-petioled. Flowers tubular to bell-shaped, 1-1.5 inches (2.5-4 cm) long, pink-purple to lavender with darker nectar guides on the lower lip, borne in loose terminal and axillary panicles. The corolla mouth is open and inflated, characteristic of the Penstemon subgenus Saccanthera. Bloom occurs May through July, peaking in late May and June at lower elevations. Seed capsules dry, two-valved, 0.3-0.4 inch (8-10 mm) long, ripening in August. Plants spread slowly by short rhizomes; clumps reach 12-18 inches (30-45 cm) wide within 3-4 years. Foliage persists as a basal rosette in zones 8-9 and dies back to ground level in zone 7. Adapted to shaded forest understory rather than the open dry sites that suit most Penstemon species; cannot tolerate full sun combined with summer drought.
Native Range
Native to coastal northern California and southwestern Oregon, primarily in the Klamath Mountains, Coast Ranges, and inner North Coast Ranges. Found in coniferous forest understory, shaded streambanks, and forest openings under Pseudotsuga menziesii, Sequoia sempervirens, and mixed evergreen forest at 200-5,000 feet (60-1,500 m) elevation.Suggested Uses
Used in shaded native plant gardens, woodland edges, and dry shade plantings under high-canopy conifers at 12-18 inch (30-45 cm) spacing in zones 7-9. Restoration plantings in northern California and southern Oregon include this species for forest understory diversification. Container culture is rare; the species responds poorly to root confinement and is grown almost exclusively in-ground.How to Identify
Appearance
Size & Dimensions
Height1' - 3'
Width/Spread1' - 1'6"
Reaches mature size in approximately 4 years
Bloom Information
May through July, with peak bloom from late May through June at low elevations and continuing into August above 4,000 feet (1,200 m). Individual flowers last 4-6 days; each panicle blooms for 3-4 weeks. Bloom is reduced after dry winters and in years with cool June temperatures.Detailed Descriptions
Flower Description
Pink-purple to lavenderFoliage Description
GreenGrowing Conditions
Sun Requirements
Requires 2-5 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
Care & Maintenance
Care Guide
Plants establish within one season from 4-inch (10 cm) container stock planted in fall in zones 7-9 to use winter rainfall. Maintain consistent moisture during the first two summers; mature plants tolerate 2-3 weeks without water in shaded sites but decline in summer drought combined with full sun. Plants are short-lived in heavy clay soils due to crown rot; lifespan 4-7 years in well-drained loam. Powdery mildew may develop on foliage in late summer; cosmetic only. Self-seeds modestly in undisturbed leaf litter, producing 2-5 volunteers annually.Pruning
Cut spent flower stems back to basal foliage in late July or August to reduce self-seeding; alternatively, leave for fall seed dispersal in naturalistic plantings. Remove yellowing or mildewed foliage at the base in fall; cut entire plant to ground level after first hard frost in zone 7.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
summerfall
Maintenance Level
lowContainer Growing
Minimum container size: 3 gallons