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Penstemon serrulatus (Cascade Penstemon)

Serrulate Penstemon, Serrulate Beardtongue, Cascade Penstemon, Cascade Beardtongue, Coast Penstemon, Coast Beardtongue, Penstemon diffusus

Penstemon serrulatus, Serrulate Penstemon, Serrulate Beardtongue, Cascade Penstemon, Cascade Beardtongue, Coast Penstemon, Coast Beardtongue, Purple Penstemon, Purple Beardtongue
Penstemon serrulatus, Serrulate Penstemon, Serrulate Beardtongue, Cascade Penstemon, Cascade Beardtongue, Coast Penstemon, Coast Beardtongue, Purple Penstemon, Purple Beardtongue

Penstemon serrulatus (Cascade Penstemon) is a semi-evergreen subshrub with several ascending to erect stems boasting dense, one-sided clusters of deep blue to purple, trumpet-shaped flowers in early to late summer. The blossoms attract bees, hummingbirds, and numerous pollinators. Arising from a woody base, the stems are clad with glossy, oval to lance-shaped, dark green leaves that are conspicuously toothed on the margin. Cascade Penstemon is native to moist woods and rock faces of the humid transition zone west of the Cascade Mountain crest. It is considered to be one of the most adaptable penstemons and is cold tolerant.

  • Grows up to 12-24 in. tall (30-60 cm) and 10-12 in. wide (25-30 cm).
  • Performs best in full sun in moist, well-drained soils. The soil should not be too dry.
  • Provides a charming impact in beds and borders, cottage gardens, or along ponds and streams.
  • Keep an eye out for slugs, snails, aphids, gray mold, powdery mildew, and fungal leaf spot.
  • Deadhead after flowering.
  • Take softwood cuttings in early summer or semi-ripe cuttings in midsummer. Divide in spring or propagate by seed in late winter or spring.
  • Native to Alaska, Oregon, Washington and British Columbia.

Requirements

Hardiness 3 - 9
Heat Zones 1 - 9
Plant Type Shrubs
Plant Family Plantaginaceae
Genus Penstemon
Exposure Full Sun
Season of Interest Summer (Early, Mid, Late)
Height 1' - 2'
(30cm - 60cm)
Spread 10" - 1'
(30cm - 30cm)
Spacing 12" (30cm)
Maintenance Low
Water Needs Average, High
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained
Characteristics Showy, Semi-Evergreen
Native Plants Alaska, Oregon, Pacific Northwest, United States, Washington
Attracts Bees, Birds, Butterflies, Hummingbirds
Garden Uses Beds And Borders, Ponds And Streams
Garden Styles Informal and Cottage
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Alternative Plants to Consider

Penstemon 'Onyx and Pearls', Onyx and Pearls Beardtongue, Beardtongue 'Onyx and Pearls', White Penstemon, White Beardtongue, Black Penstemon, Black Beardtongue
Penstemon centranthifolius, Scarlet Bugler, Red Penstemon, Red Beardtongue, California Native Perennial, California Native Plant
Penstemon heterophyllus, Bunchleaf Penstemon, Bunchleaf Beardtongue, Foothill Penstemon, Foothill Beardtongue, California Native Plants
Penstemon 'Midnight Masquerade',  Beardtongue 'Midnight Masquerade', Purple Penstemon, Purple Beardtongue, Lavender Penstemon, Lavender Beardtongue
Penstemon confertus, Yellow Penstemon, Yellow Beardtongue
Penstemon palmeri, Palmer's Penstemon, Palmer's Beardtongue, Scented Penstemon, Scented Beardtongue, Pink Penstemon, Pink Beardtongue

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While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.
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Requirements

Hardiness 3 - 9
Heat Zones 1 - 9
Plant Type Shrubs
Plant Family Plantaginaceae
Genus Penstemon
Exposure Full Sun
Season of Interest Summer (Early, Mid, Late)
Height 1' - 2'
(30cm - 60cm)
Spread 10" - 1'
(30cm - 30cm)
Spacing 12" (30cm)
Maintenance Low
Water Needs Average, High
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained
Characteristics Showy, Semi-Evergreen
Native Plants Alaska, Oregon, Pacific Northwest, United States, Washington
Attracts Bees, Birds, Butterflies, Hummingbirds
Garden Uses Beds And Borders, Ponds And Streams
Garden Styles Informal and Cottage
How Many Plants
Do I Need?
Learn Now
Explore Great Plant Combination Ideas
Penstemon
Guides with
Penstemon
Not sure which Penstemon to pick?
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