Penstemon serrulatus (Cascade Penstemon)
Serrulate Penstemon, Serrulate Beardtongue, Cascade Penstemon, Cascade Beardtongue, Coast Penstemon, Coast Beardtongue, Penstemon diffusus
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 |
Alternative Plants to Consider
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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 |
